‘Yes,’ he said. ‘The key is in his pocket.’

Hugo drew out a cigarette-case and lighted a cigarette. He spoke rather hoarsely.

‘It seems all quite clear,’ he said. ‘My uncle shut himself up in here, scrawled that message on a piece of paper, and then shot himself.’

Poirot nodded meditatively. Hugo went on:

‘But I don’t understand why he sent for you. What was it all about?’

‘That is rather more difficult to explain. While we are waiting, Mr Trent, for the authorities to take charge, perhaps you will tell me exactly who all the people are whom I saw tonight when I arrived?’

‘Who they are?’ Hugo spoke almost absently. ‘Oh, yes, of course. Sorry. Shall we sit down?’ He indicated a settee in the farthest corner of the room from the body. He went on, speaking jerkily: ‘Well, there’s Vanda—my aunt, you know. And Ruth, my cousin. But you know them. Then the other girl is Susan Cardwell. She’s just staying here. And there’s Colonel Bury. He’s an old friend of the family. And Mr Forbes. He’s an old friend, too, beside being the family lawyer and all that. Both the old boys had a passion for Vanda when she was young, and they still hang round in a faithful, devoted sort of way. Ridiculous, but rather touching. Then there’s Godfrey Burrows, the Old Man’s—I mean my uncle’s—secretary, and Miss Lingard, who’s here to help him write a history of the Chevenix-Gores. She mugs up historical stuff for writers. That’s the lot, I think.’

Poirot nodded. Then he said:

‘And I understand you actually heard the shot that killed your uncle?’

‘Yes, we did. Thought it was a champagne cork—at least, I did. Susan and Miss Lingard thought it was a car backfiring outside—the road runs quite near, you know.’

‘When was this?’

‘Oh, about ten past eight. Snell had just sounded the first gong.’

‘And where were you when you heard it?’

‘In the hall. We—we were laughing about it—arguing, you know, as to where the sound came from. I said it came from the dining-room, and Susan said it came from the direction of the drawing-room, and Miss Lingard said it sounded like upstairs, and Snell said it came from the road outside, only it came through the upstairs windows. And Susan said, ‘Any more theories?’ And I laughed and said there was always murder! Seems pretty rotten to think of it now.’

His face twitched nervously.

‘It did not occur to anyone that Sir Gervase might have shot himself?’

‘No, of course not.’

‘You have, in fact, no idea why he should have shot himself?’

Hugo said slowly:

‘Oh, well, I shouldn’t say that—’

‘You have an idea?’

‘Yes—well—it’s difficult to explain. Naturally I didn’t expect him to commit suicide, but all the same I’m not frightfully surprised. The truth of it is that my uncle was as mad as a hatter, M. Poirot. Everyone knew that.’

‘That strikes you as a sufficient explanation?’