Since I am now recalling that period in my life following the Mannering case, it is perhaps worth mentioning here my unexpected reunion with Colonel Chamberlain after all those years. It is perhaps surprising, given the role he played at such a pivotal juncture in my childhood, that we had not kept in closer contact. But for whatever reason, we had failed to do so, and when I did meet him again – a month or two after that encounter with Miss Hemmings at the Waldorf – it was quite by chance.

I was standing in a bookshop on the Charing Cross Road one rainy afternoon, examining an illustrated edition of Ivanhoe. I had been aware for some time of someone hovering close behind me, and assuming he was wishing access to that part of the shelf, had moved aside. But then when the person continued to loiter around me, I finally turned.

I recognised the colonel immediately, for his physical features had hardly changed. However, through adult eyes, he appeared to me meeker and shabbier than the figure from my boyhood. He was standing there in a mackintosh, regarding me shyly, and only when I exclaimed: ‘Ah, Colonel!’ did he smile and hold out his hand.

‘How are you, my boy? I was sure it was you. My goodness! How are you, my boy?’

Although tears had appeared in his eyes, his manner remained awkward, as though he were afraid I might be annoyed at this reminder of the past. I did my best to convey delight at seeing him again, and as a downpour commenced outside, we stood there exchanging conversation in the cramped bookshop. I discovered that he was still living in Worcestershire, that he had come to London to attend a funeral and had decided ‘to make a few days of it’. When I asked where he was staying, he answered vaguely, leading me to suspect he had taken modest lodgings. Before parting, I invited him to dine with me the following evening, a suggestion he took up with enthusiasm, though he seemed taken aback when I mentioned the Dorchester. But I continued to insist – ‘It's the least I can do after all your past kindness,’ I had pleaded – until finally he gave in.

Looking back now, my choice of the Dorchester strikes me as the height of inconsideration. I had, after all, already surmised that the colonel was short of funds; I should have seen too how wounding it would be for him not to pay at least his half of the bill. But in those days such things never occurred to me; I was much too concerned, I suspect, about impressing the old man with the full extent of my transformation since he had last seen me.

In this latter aim, I was probably rather successful. For as it happened, I had just around that point been taken to the Dorchester on two occasions, so that on the evening I met Colonel Chamberlain there, the sommelier greeted me with a ‘nice to see you again, sir’. Then, after he had witnessed me exchanging witticisms with the maître d’ as we started on our soup, the colonel broke into sudden laughter.

‘And to think,’ he said, ‘this is the same little squirt I had snivelling at my side on that boat!’

He gave a few more laughs, then broke off abruptly, perhaps fearing he should never have alluded to the subject. But I smiled calmly and said:

‘I must have been a trial to you on that trip, Colonel.’

The old man's face clouded for a moment. Then he said solemnly: ‘Considering the circumstances, I thought you were extremely brave, my boy. Extremely brave.’

At this stage, I recall, there was a slightly awkward silence, which was broken when we both commented on the fine flavour of our soup. At the next table, a large lady with much jewellery was laughing gaily, and the colonel glanced rather indiscreetly towards her. Then he appeared to come to a decision.

‘You know, it's funny,’ he said. ‘I was thinking about it, before I came out tonight. That time you and I first met. I wonder if you remember, my boy. I don't suppose you do. After all, you had so much else on your mind then.’

‘On the contrary,’ I said, ‘I have the most vivid memory of the occasion.’

This was no lie. Even now, if I were for a moment to close my eyes, I could with ease transport myself back to that bright morning in Shanghai and the office of Mr Harold Anderson, my father's superior in the great trading company of Morganbrook and Byatt. I was sitting in a chair that smelt of polished leather and oak, the sort of chair normally found behind some impressive desk, but which, on this occasion, had been pulled out into the centre of the room. I could sense it was a chair reserved for only the most important of personages, but on this occasion, owing to the gravity of the circumstances, or perhaps as a sort of consolation, it had been given to me. I can remember that, no matter how I tried, I could not find a dignified way to sit in it; in particular, I could discover no posture which would enable me to keep both elbows at once upon its finely carved arms. Moreover, I had on that morning a brand new jacket made from some coarse grey material – where it had come from, I do not know – and I was most self-conscious about the ugly way I had been made to button it almost to my chin.

The room itself had tall grand ceilings, a large map on one wall, and behind Mr Anderson's desk, great windows through which the sun was beating and a breeze blowing. I should think there were ceiling fans moving above me, though I do not actually remember this. What I do remember is that I was sitting in that chair in the middle of the room, the centre of solemn concern and discussion. All around me, adults were conferring, most of them on their feet; sometimes a few would drift over to the windows, their voices lowering as they argued a point. I remember too being surprised by the way Mr Anderson himself, a tall greying man with a large moustache, behaved towards me as though we were old friends – so much so that for a while I assumed we had known each other when I was younger and that I had forgotten him. Only much later did I ascertain that we could not possibly have met until that morning. In any case, he had assumed for himself the role of uncle, continually smiling at me, patting my shoulder, nudging me and winking. Once he offered me a cup of tea, saying: ‘Now, Christopher, this will cheer you up,’ and had bent right down to peer at me as I had taken it. After that came more murmuring and conferring around the room. Then Mr Anderson appeared in front of me again and said:

‘So then, Christopher. It's all decided. This is Colonel Chamberlain. He's most kindly agreed to see you safe to England.’

I remember at this point a hush descending over the room. In fact, my impression was that all the adults shrank back until they were lining the walls like spectators. Mr Anderson too withdrew with a final encouraging smile. It was then that I first laid eyes on Colonel Chamberlain. He came up to me slowly, bent down to look into my face, then held out his hand. I had a feeling I should stand up to shake it, but he had thrust it out so quickly, and I had felt so fixed to that chair, that I had grasped his hand still sitting. Then I remember him saying:

‘My poor lad. First your father. Now your mother. Must feel like the whole world's collapsed around your ears. But we'll go to England tomorrow, the two of us. Your aunt's waiting for you there. So be brave. You'll soon pick up the pieces again.’

For a moment I was quite unable to find my voice. When I finally did so, I said: ‘It's awfully kind of you, sir. I'm very grateful for your offer, and I hope you don't think me very rude. But if you don't mind, sir, I think I oughtn't to go to England just now.’ Then, when the colonel did not respond immediately, I went on:

‘Because you see, sir, the detectives are working extremely hard to find my mother and father. And they're the very best detectives in Shanghai. I think they're bound to find them very soon.’

The colonel was nodding. ‘I'm sure the authorities are doing everything possible.’

‘So you see, sir, though I very much appreciate your kindness, I think my going to England, it won't be necessary after all.’

I remember a murmur passing around the room at this point. The colonel went on nodding, as though weighing things up carefully.

‘You may well be right, my boy,’ he said eventually. ‘I sincerely hope you are. But just in case, why don't you come with me anyway? Then once your parents are found, they can send for you. Or who knows? Perhaps they'll decide to come to England too. So what do you say? Let's you and me go to England tomorrow. Then we can wait and see what happens.’

‘But you see, sir, excuse me. But you see, the detectives looking for my parents. They're the very best detectives.’

I am not sure what exactly the colonel said to this. Perhaps he just went on nodding. In any case, the next moment, he leaned in even closer to me and placed a hand on my shoulder.

‘Look here. I realise how it must feel. Entire world's collapsed about your ears. But you've got to be brave. Besides, your aunt in England. She's expecting you, don't you see? Can't very well let the lady down at this stage, can we?’

When, sitting over our soup that evening, I related to him my memory of these last words of his, I rather expected him to laugh. Instead, he said solemnly:

‘I felt so sorry for you, my boy. So terribly sorry.’ Then perhaps sensing he had misjudged my mood, he gave a short laugh and said more lightly: ‘I remember waiting at the harbour with you. I kept saying: “Look here, we're going to have a lot of fun on that ship, aren't we? We're going to have a jolly good time.” And you just kept saying: “Yes, sir. Yes, sir. Yes, sir.”’

I allowed him, for the next several minutes, to drift through reminiscences concerning various of his old acquaintances who had been present in Mr Anderson's office that morning. Without exception, their names meant nothing to me. Then the colonel paused and a frown crossed his face.

‘As for that Anderson himself,’ he said eventually, ‘that chap always gave me an uneasy feeling. Something fishy about him. There was something fishy about the whole damn business, if you ask me.’

No sooner had he said this than he looked up at me with a start. Then before I could respond, he began to talk again rapidly, moving us on to what he no doubt considered the safer territory of our voyage to England. Before long, he was chuckling to himself as he recounted memories of our fellow passengers, the ship's officers, amusing little incidents I had long forgotten or had not registered in the first place. He was enjoying himself and I encouraged him to do so, often pretending to remember something just to please him. However, as he continued with these reminiscences, I found myself becoming somewhat irritated. For gradually, from behind his cheerful anecdotes, there was emerging a picture of myself on that voyage to which I took exception. His repeated insinuation was that I had gone about the ship withdrawn and moody, liable to burst into tears at the slightest thing. No doubt the colonel had an investment in giving himself the role of an heroic guardian, and after all this time, I saw it was as pointless as it was unkind to contradict him. But as I say, I began to grow steadily more irritated. For according to my own, quite clear memory, I adapted very ably to the changed realities of my circumstances. I remember very well that, far from being miserable on that voyage, I was positively excited about life aboard the ship, as well as by the prospect of the future that lay before me. Of course, I did miss my parents at times, but I can remember telling myself there would always be other adults I would come to love and trust. In fact, there were a number of ladies on the voyage who had heard what had happened to me and who, for a time, came fussing around me with pitying expressions, and I can recall feeling much the same irritation with them as I did towards the colonel that evening at the Dorchester. The fact was, I was not nearly as distressed as the adults around me seemed to suppose. As far as I can recall, there was only a single instance during the whole of that long voyage when I might conceivably have merited that title of ‘snivelling little squirt’, and even that occurred on the very first day of our journey.

The sky that morning was overcast, the waters around us very muddy. I was standing on the deck of the steamer gazing back towards the harbour, towards the messy shoreline of boats, gangplanks, mud huts, dark wood jetties, behind them the large buildings of the Shanghai Bund, all now fading together into a single blur.

‘Well, lad?’ the colonel's voice had said near me. ‘Think you'll be back again one day?’

‘Yes, sir. I expect I'll come back.’

‘We'll see. Once you're settled in England, I dare say you'll forget all this quickly enough. Shanghai's not a bad place. But eight years is about as much as I can take of it, and I expect you've had about as much as you need. Much more, you'll be turning into a Chinaman.’

‘Yes, sir.’

‘Look here, old fellow. You really ought to cheer up. After all, you're going to England. You're going home.’

It was this last remark, this notion that I was ‘going home’, which caused my emotions to get the better of me for – I am certain of this – the first and last time on that voyage. Even then, my tears were more of anger than sorrow. For I had deeply resented the colonel's words. As I saw it, I was bound for a strange land where I did not know a soul, while the city steadily receding before me contained all I knew. Above all, my parents were still there, somewhere beyond that harbour, beyond that imposing skyline of the Bund, and wiping my eyes, I had cast my gaze towards the shore one last time, wondering if even now I might catch sight of my mother – or even my father – running on to the quay, waving and shouting for me to return. But I was conscious even then that such a hope was no more than a childish indulgence. And as I watched the city that had been my home grow less and less distinct, I remember turning to the colonel with a cheerful look and saying: ‘We should be reaching the sea fairly soon, don't you think so, sir?’

But I believe I managed to betray none of my irritation with the colonel that evening. Certainly, by the time he boarded a taxicab in South Audley Street, and we said our farewells, he was in a splendid mood. It was only when I heard of his death just over a year later that I felt somewhat guilty I had not been warmer towards him that evening at the Dorchester. He had, after all, once done me a good turn, and from all I had observed, had been a very decent man. But I suppose the role he had played in my life – the fact of his being so overwhelmingly associated with what happened at that point – will ensure he remains for ever an ambivalent figure in my memory.

For at least three or four years after that Waldorf episode, Sarah Hemmings and I had little to do with one another. I remember seeing her once during this period at a cocktail party in a flat in Mayfair. The event was very crowded, but I did not know many of those there and had decided to leave early. I was making my way towards the door, when I spotted Sarah Hemmings talking with someone, standing directly in my path. My first instinct was to turn and go another way. But this was around the time of my success with the Roger Parker case, and it did occur to me to wonder if Miss Hemmings would still dare to be quite so high-handed as she had been at the Waldorf a few years earlier. I thus continued to squeeze my way past the guests and made sure to pass right in front of her. As I did so, I saw her gaze move to check over my features. A look of bemusement crossed her face as she struggled to remember who I was. Then I saw recognition dawn, and without a smile, without a nod, she turned her gaze back to the person to whom she was talking.

But I hardly gave such an incident any thought. For it came during a period when I was deeply engrossed in many challenging cases. And although this was still a good year before my name acquired anything of the standing it has today, I was already beginning to appreciate for the first time the scale of responsibility that befalls a detective with any sort of renown. I had always understood, of course, that the task of rooting out evil in its most devious forms, often just when it is about to go unchecked, is a crucial and solemn undertaking. But it was not until my experience of such cases as the Roger Parker murder that it came home to me just how much it means to people – and not only those directly concerned, but the public at large – to be cleansed of such encroaching wickedness. As a result, I became more determined than ever not to be diverted by the more superficial priorities of London life. And I began to understand, perhaps, something of what had made it possible for my parents to take the stand they had. In any case, the likes of Sarah Hemmings did not much impinge on my thoughts during that time, and it is even possible I would have forgotten of her existence altogether had I not run into Joseph Turner that day in Kensington Gardens.

I was at that time investigating a case in Norfolk and had returned to London for a few days with the intention of studying the extensive notes I had made. It was while I was strolling around Kensington Gardens one grey morning, pondering the many curious details surrounding the victim's disappearance, that I was hailed from afar by a figure I quickly recognised to be Turner, a man I had come to know vaguely from my social rounds. He came hurrying up to me, and after asking why I was so rarely ‘seen about the place these days’, invited me to a dinner he and a friend were giving in a restaurant that evening. When I politely declined on the grounds that my present case was demanding all my time and attention, he said:

‘Shame. Sarah Hemmings is coming along, and she's so wanting to have a good chat with you.’

‘Miss Hemmings?’

‘Remember her, don't you? She certainly remembers you. Said you got to know each other a bit a few years ago. She's always complaining how you're no longer to be found.’

Resisting the urge to make some comment, I said simply: ‘Well, please do give her my good wishes.’

I left Turner fairly promptly after that, but on returning to my desk I confess I found myself somewhat distracted by this report of Miss Hemmings's wishing to see me. In the end, I told myself that in all likelihood Turner had made some mistake; or at the least, was exaggerating his point in an effort to entice me to his dinner. But then over the following months a number of similar reports reached my ears. Sarah Hemmings had been heard expressing annoyance at how, despite our once having been friends, I had now become impossible for her to find. I heard from several sources, moreover, how she was threatening to ‘ferret me out’. Then finally, last week, while I was staying in the village of Shackton, in Oxfordshire, to investigate the Studley Grange business, Miss Hemmings turned up in person, presumably with the intention of doing just that.

I had found the walled garden – containing the pond where Charles Emery's body had been discovered – in the lower grounds of the house. Four stone steps had brought me down into a rectangular space so perversely sheltered from the sun that even on that bright morning everything around me was in shadow. The walls themselves were covered with ivy, but somehow one could not avoid the impression of having stepped into a roofless prison cell.

The pond dominated this enclosure. Though several people had told me it contained goldfish, I could see no sign of life; in fact, it was hard to imagine how anything could thrive in such dank water – a fitting place indeed to discover a corpse. Surrounding the pond was a circle of square mossy slabs embedded into the mud. I would suppose I had been examining this area for about twenty minutes – I was on my front, scrutinising with my magnifying glass one of the slabs that projected over the water – when I became conscious of someone observing me. At first I assumed this to be some family member wishing yet again to pester me with questions. Since earlier I had insisted on uninterrupted time, I decided, at the cost of appearing rude, to pretend not to have noticed anything.

Then eventually I heard the sound of a shoe scraping on stone somewhere near the entrance to the garden. By then it was starting to seem unnatural that I should remain on my belly for such a long time, and in any case, I had exhausted the investigations I could usefully carry out in such a posture. Moreover, I had not entirely forgotten I was lying at almost the exact spot where a murder had been committed, and that the murderer was still at large. A chilly sensation passed through me as I clambered to my feet, and dusting my clothes, turned to face the intruder.

The sight of Sarah Hemmings did of course rather surprise me, but I am sure nothing unusual showed on my face. I had set my features to convey annoyance, and I would suppose that is what she saw, for her opening words to me were:

‘Oh! Didn't mean to spy on you. But it seemed too good an opportunity. To watch the great man at his work, I mean.’

I searched her face carefully, but could detect no sarcasm. Nevertheless, I kept my voice cold as I said: ‘Miss Hemmings. This is most unexpected.’

‘I heard you were here. I'm spending a few days with my friend in Pemleigh. It's only just up the road.’

She paused, no doubt expecting me to respond. When I remained silent, she showed no sign of being perturbed, but instead came walking towards me.

‘I'm quite a good friend of the Emerys, did you know?’ she continued. ‘Awful business, this murder.’

‘Yes, awful.’

‘Ah. So you too believe it to be murder. Well, I suppose that sort of clinches it. Do you have a theory, Mr Banks?’

I gave a shrug. ‘I've formed a few ideas, yes.’

‘It's too bad for the Emerys they didn't think to ask you for help when it all first happened last April. I mean to say, bringing Celwyn Henderson on to a case like this! What did they expect? That man should have been put out to pasture long ago. Just shows you how out of touch people get living out here. Anyone in London could have told them all about you, of course.’

This last remark did, I have to confess, intrigue me somewhat, so that after a moment's hesitation, I found myself asking her: ‘Excuse me, but told them what, exactly?’

‘Why, that you're the most brilliant investigative mind in England, of course. We could all have told them that last spring, but the Emerys – it's taken them this long to cotton on. Better late than never, perhaps, but I suppose the trail's gone rather cold for you by now.’

‘As it happens, there are some advantages in coming to a case after some time has elapsed.’

‘Really? How fascinating. I always thought it was essential to get there quick, to pick up the scent, you know.’

‘On the contrary, it's never too late to, as you put it, pick up the scent.’

‘But isn't it so depressing, how this crime's eaten away at people's spirits here? And not just the household. It's the whole of Shackton that's started to rot. This used to be a happy and thriving market town. Now look at them, they barely meet each other's eyes. This whole business has dragged them down into a mire of suspicion. I tell you, Mr Banks, if you can solve this thing, they'll remember you here for ever.’

‘Do you really think so? That would be curious.’

‘No doubt about it. They'd be so grateful. Yes, they'll be talking about you here for generations.’

I let out a short laugh. ‘You seem to know the village well, Miss Hemmings. And I thought you spent all your time in London.’

‘Oh, I can only take so much of London, then I've just got to come away. I'm not a city girl at heart, you know.’

‘You surprise me. I always thought you were much drawn to city life.’

‘You're quite right, Mr Banks.’ A note of resentment had come into her voice, as though I had tricked her into a corner. ‘Something does draw me to the city. It does have its … its attractions for me.’ For the first time, she turned away from me and glanced around the walled garden. ‘Which reminds me,’ she said. ‘Well, to be honest, it doesn't remind me at all. Why should I pretend? I've been thinking of it all the time we've been talking. I wanted to ask a favour of you.’

‘And what's that, Miss Hemmings?’

‘Reliable sources tell me you've been invited to this year's Meredith Foundation dinner. Is that right?’

I paused slightly before replying: ‘Yes. That's correct.’

‘Quite a thing, to be invited at your age. I've heard this year it's in honour of Sir Cecil Medhurst.’

‘Yes, I believe so.’

‘I've heard too that Charles Wolfe is expected to attend.’

‘The violinist?’

She laughed brightly. ‘Does he do something else? And Thomas Byron too, apparently.’

She had become visibly excited, but now she once again turned away and gazed at our surroundings with a slight shudder.

‘Did you say,’ I asked eventually, ‘you wished me to grant you a favour?’

‘Oh yes, yes. I wanted you to … I wished you to ask me to accompany you. To the Meredith Foundation dinner.’

She was now holding me with an intense look. It took me a moment to find a response, but when I did so, I spoke quite calmly.

‘I'd like to oblige you, Miss Hemmings. But unfortunately I've already replied to the organisers some days ago. I fear it'll be rather late to inform them of my wish to bring a guest …’

‘Nonsense!’ she broke in angrily. ‘Yours is the name on everyone's lips just now. If you wish to bring a companion, they'd be only too pleased. Mr Banks, you aren't about to let me down, are you? That would be quite unworthy of you. After all, we've been good friends for some time now.’

It was this last remark – reminding me as it did of the actual history of our ‘friendship’ – that brought me back to myself.

‘Miss Hemmings,’ I said with finality, ‘this is hardly a favour within my power to grant.’

But there was now a determined look in Sarah Hemmings's eyes.

‘I know all the details, Mr Banks. At Claridge's Hotel. Next Wednesday evening. I mean to be there. I shall look forward to the evening, and I shall be waiting for you in the lobby.’

‘The lobby of Claridge's is, as far as I'm aware, open to respectable members of the public. If you choose to stand there next Wednesday evening, there is nothing I can do to prevent you, Miss Hemmings.’

She looked at me very carefully, now uncertain about my intentions. Finally she said: ‘Then you shall most certainly see me there next Wednesday, Mr Banks.’

‘As I've said, that is your affair, Miss Hemmings. Now, if you'll excuse me.’