‘I invited it,’ he said, ‘and I got it. In a sense, I suppose I committed the unforgivable offence of failing to lead trumps. Legge was trumps. Go on, my dear Alleyn. Expound. Is it Locke who says that it is one thing to show a man he is in error and another to convince him of the truth? You have shown me my error. Pray reveal the whole truth.’

‘From the first,’ said Alleyn, ‘it seemed obvious that Legge was our man. Mr Harper realized that, and so, sir, did you. This afternoon I told Harper that Fox and I had arrived at the same conclusion. You asked me not to give you our theory, but before and after you came into Illington we discussed the whole thing. Harper was for arresting him there and then, and I, mistakenly perhaps, thought that we should give him more rope. I thought that on our evidence, which rests so much upon conjecture, we would not establish a prima facie case.’

‘What is your evidence beyond the tedious—well, go on.’