‘I don’t really see what my personal relationships to people has to do with the matter in hand, M. Poirot.’

‘But I think, Lord Mayfield, that they may have a good deal to do with it. You agreed, did you not, that my theory of someone in the drawing-room was a possible one?’

‘Yes. In fact, I agree with you that that is what must have happened.’

‘We will not say “must.” That is too self-confident a word. But if that theory of mine is true, who do you think the person in the drawing-room could have been?’

‘Obviously Mrs Vanderlyn. She had been back there once for a book. She could have come back for another book, or a handbag, or a dropped handkerchief—one of a dozen feminine excuses. She arranges with her maid to scream and get Carlile away from the study. Then she slips in and out by the windows as you said.’

‘You forget it could not have been Mrs Vanderlyn. Carlile heard her call the maid from upstairs while he was talking to the girl.’

Lord Mayfield bit his lip.

‘True. I forgot that.’ He looked throughly annoyed.

‘You see,’ said Poirot gently. ‘We progress. We have first the simple explanation of a thief who comes from outside and makes off with the booty. A very convenient theory as I said at the time, too convenient to be readily accepted. We have disposed of that. Then we come to the theory of the foreign agent, Mrs Vanderlyn, and that again seems to fit together beautifully up to a certain point. But now it looks as though that, too, was too easy—too convenient—to be accepted.’

‘You’d wash Mrs Vanderlyn out of it altogether?’

‘It was not Mrs Vanderlyn in the drawing-room. It may have been an ally of Mrs Vanderlyn’s who committed the theft, but it is just possible that it was committed by another person altogether. If so, we have to consider the question of motive.’

‘Isn’t this rather far-fetched, M. Poirot?’

‘I do not think so. Now what motives could there be? There is the motive of money. The papers may have been stolen with the object of turning them into cash. That is the simplest motive to consider. But the motive might possibly be something quite different.’

‘Such as—’

Poirot said slowly:

‘It might have been done definitely with the idea of damaging someone.’

‘Who?’

‘Possibly Mr Carlile. He would be the obvious suspect. But there might be more to it than that. The men who control the destiny of a country, Lord Mayfield, are particularly vulnerable to displays of popular feeling.’

‘Meaning that the theft was aimed at damaging me?’

Poirot nodded.

‘I think I am correct in saying, Lord Mayfield, that about five years ago you passed through a somewhat trying time. You were suspected of friendship with a European Power at that time bitterly unpopular with the electorate of this country.’

‘Quite true, M. Poirot.’

‘A statesman in these days has a difficult task. He has to pursue the policy he deems advantageous to his country, but he has at the same time to recognize the force of popular feeling. Popular feeling is very often sentimental, muddle-headed, and eminently unsound, but it cannot be disregarded for all that.’