As I say, up till the Monday evening, my narrative might have been that of Poirot himself. I played Watson to his Sherlock. But after Monday our ways diverged. Poirot was busy on his own account. I got to hear of what he was doing, because in King's Abbot, you get to hear of everything, but he did not take me into his confidence beforehand. And I, too, had my own preoccupations.

On looking back, the thing that strikes me most is the piecemeal character of this period. Everyone had a hand in the elucidation of the mystery. It was rather like a jigsaw puzzle to which everyone contributed their own little piece of knowledge or discovery. But their task ended there. To Poirot alone belongs the renown of fitting those pieces into their correct place.

Some of the incidents seemed at the time irrelevant and unmeaning. There was, for instance, the question of the black boots. But that comes later… To take things strictly in chronological order, I must begin with the summons from Mrs Ackroyd.

She sent for me early on Tuesday morning, and since the summons sounded an urgent one, I hastened there, expecting to find her in extremis.

The lady was in bed. So much did she concede to the etiquette of the situation. She gave me her bony hand, and indicated a chair drawn up to the bedside.

'Well, Mrs Ackroyd,' I said, 'and what's the matter with you?' I spoke with that kind of spurious geniality which seems to be expected of general practitioners.

'I'm prostrated,' said Mrs Ackroyd in a faint voice. 'Absolutely prostrated. It's the shock of poor Roger's death.

They say these things often aren't felt at the time, you know.

It's the reaction afterwards.' It is a pity that a doctor is precluded by his profession from being able sometimes to say what he really thinks.

I would have given anything to be able to answer 'Bunkum!' Instead, I suggested a tonic. Mrs Ackroyd accepted the tonic. One move in the game seemed now to be concluded.

Not for a moment did I imagine that I had been sent for because of the shock occasioned by Ackroyd's death. But Mrs Ackroyd is totally incapable of pursuing a straightforward course on any subject. She always approaches her object by tortuous means. I wondered very much why it was she had sent for me.

'And then that scene - yesterday,' continued my patient.

She paused as though expecting me to take up a cue.

'What scene?' 'Doctor, how can you? Have you forgotten? That dreadful little Frenchman - or Belgian - or whatever he is.

Bullying us all like he did. It has quite upset me. Coming on the top of Roger's death.' 'I'm very sorry, Mrs Ackroyd,' I said.

'I don't know what he meant - shouting at us like hell. I should hope I know my duty too well to dream of concealing anything. I have given the police every assistance in my power.' Mrs Ackroyd paused, and I said, 'Quite so.' I was beginning to have a glimmering of what all the trouble was about.

'No one can say that I have failed in my duty,' continued Mrs Ackroyd. 'I am sure Inspector Raglan is perfectly satisfied. Why should this little upstart of a foreigner make a fuss? A most ridiculous-looking creature he is too - just like a comic Frenchman in a revue. I can't think why Flora insisted on bringing him into the case. She never said a word to me about it. Just went off and did it on her own.

Flora is too independent. I am a woman of the world and her mother. She should have come to me for advice first.' I listened to all this in silence.

'What does he think? That's what I want to know. Does he actually imagine I'm hiding something? He - he - positively accused me yesterday.' I shrugged my shoulders.

'It is surely of no consequence, Mrs Ackroyd,' I said.

'Since you are not concealing anything, any remarks he may have made do not apply to you.' Mrs Ackroyd went off at a tangent, after her usual fashion.

'Servants are so tiresome,' she said. 'They gossip, and talk amongst themselves. And then it gets round - and all the time there's probably nothing in it at all.' 'Have the servants been talking?' I asked. 'What about?' Mrs Ackroyd cast a very shrewd glance at me. It quite threw me off my balance.

'I was sure you'd know, doctor, if anyone did. You were with M. Poirot all the time, weren't you?' 'I was.' 'Then of course you know. It was that girl, Ursula Bourne, wasn't it? Naturally - she's leaving. She would want to make all the trouble she could. Spiteful, that's what they are. They're all alike. Now, you being there, doctor, you must know exactly what she did say? I'm most anxious for no wrong impression should get about. After all, you don't repeat every little detail to the police, do you? There are family matters sometimes - nothing to do with the question of the murder. But if the girl was spiteful, she may have made out all sorts of things.' I was shrewd enough to see that a very real anxiety lay behind these outpourings. Poirot had been justified in his premises. Of the six people round the table yesterday, Mrs Ackroyd at least had had something to hide. It was for me to discover what that something might be.

'If I were you, Mrs Ackroyd,' I said brusquely, 'I should make a clean breast of things.' She gave a little scream.

'Oh! doctor, how can you be so abrupt. It sounds as though - as though - And I can explain everything so simply.' 'Then why not do so?' I suggested.

Mrs Ackroyd took out a frilled handkerchief, and became tearful.

'I thought, doctor, that you might put it to M. Poirot explain it, you know - because it's so difficult for a foreigner to see our point of view. And you don't know - nobody could know - what I've had to contend with. A martyrdom - a long martyrdom. That's what my life has been. I don't like to speak ill of the dead - but there it is. Not the smallest bill but it had all to be gone over - just as though Roger had had a few miserly hundreds a year instead of being (as Mr Hammond told me yesterday) one of the wealthiest men in these parts.' Mrs Ackroyd paused to dab her eyes with the frilled handkerchief.

'Yes,' I said encouragingly. 'You were talking about bills?' 'Those dreadful bills. And some I didn't like to show Roger at all. They were things a man wouldn't understand.

He would have said the things weren't necessary. And of course they mounted up, you know, and they kept coming on' She looked at me appealingly, as though asking me to condole with her on this striking peculiarity.

'It's a habit they have,' I agreed.

And the tone altered - became quite abusive. 'I assure you, doctor, I was becoming a nervous wreck. I couldn't sleep at nights. And a dreadful fluttering round the heart.

And then I got a letter from a Scotch gentleman - as a matter of fact there were two letters - both Scotch gentlemen. Mr Bruce MacPherson was one, and the other was Colin MacDonald. Quite a coincidence.' 'Hardly that,' I said drily. 'They are usually Scotch gentlemen, but I suspect a Semitic strain in their ancestry.' 'Ten pounds to ten thousand on note of hand alone,' murmured Mrs Ackroyd reminiscently. 'I wrote to one of them, but it seemed there were difficulties.' She paused.

I gathered that we were just coming to delicate ground. I have never known anyone more difficult to bring to the point.

'You see,' murmured Mrs Ackroyd, 'it's all a question of expectations,' isn't it? Testamentary expectations. And though, of course, I expected that Roger would provide for me, I didn't know. I thought that if only I could glance over a copy of his will - not in any sense of vulgar prying - but just so that I could make my own arrangements.' She glanced sideways at me. The position was now very delicate indeed. Fortunately words, ingeniously used, will serve to mask the ugliness of naked facts.

'I could only tell this to you, dear Doctor Sheppard,' said Mrs Ackroyd rapidly. 'I can trust you not to misjudge me, and to represent the matter in the right light to M. Poirot. It was on Friday afternoon ' She came to a stop and swallowed uncertainly.