‘It’s not a case of preventing,’ said Mrs Oliver joyfully. ‘I’d have made the most awful fool of myself. I mean, what can you say about how you write books? What I mean is, first you’ve got to think of something, and when you’ve thought of it you’ve got to force yourself to sit down and write it. That’s all. It would have taken me just three minutes to explain that, and then the Talk would have been ended and everyone would have been very fed up. I can’t imagine why everybody is always so keen for authors to talk about writing. I should have thought it was an author’s business to write, not talk.’

‘And yet it is about how you write that I want to ask you.’

‘You can ask,’ said Mrs Oliver; ‘but I probably shan’t know the answer. I mean one just sits down and writes. Half a minute, I’ve got a frightfully silly hat on for the Talk – and I must take it off. It scratches my forehead.’ There was a momentary pause and then the voice of Mrs Oliver resumed in a relieved voice, ‘Hats are really only a symbol, nowadays, aren’t they? I mean, one doesn’t wear them for sensible reasons any more; to keep one’s head warm, or shield one from the sun, or hide one’s face from people one doesn’t want to meet. I beg your pardon, M. Poirot, did you say something?’

‘It was an ejaculation only. It is extraordinary,’ said Poirot, and his voice was awed. ‘Always you give me ideas. So also did my friend Hastings whom I have not seen for many, many years. You have given me now the clue to yet another piece of my problem. But no more of all that. Let me ask you instead my question. Do you know an atom scientist, Madame?’

‘Do I know an atom scientist?’ said Mrs Oliver in a surprised voice. ‘I don’t know. I suppose I may. I mean, I know some professors and things. I’m never quite sure what they actually do.’

‘Yet you made an atom scientist one of the suspects in your Murder Hunt?’

‘Oh, that! That was just to be up to date. I mean, when I went to buy presents for my nephews last Christmas, there was nothing but science fiction and the stratosphere and supersonic toys, and so I thought when I started on the Murder Hunt, “Better have an atom scientist as the chief suspect and be modern.” After all, if I’d needed a little technical jargon for it I could always have got it from Alec Legge.’

‘Alec Legge – the husband of Sally Legge? Is he an atom scientist?’