‘It’s very kind of you both,’ said Alleyn with a grin, ‘but I’m not altogether a hothouse flower. Good-bye, Sir Daniel. Thank you so much.’

They shook hands and Fox and Alleyn went out.

‘Where do we go now?’ asked Fox.

‘I think we’d better take a look at Marsdon House. Bailey ought to have finished by now. I’ll ring up from there and see if I can get an appointment with the Carrados family en masse. It’s going to be difficult, that. There seems to be no doubt that Lady Carrados is one of the blackmailing victims. Carrados himself is a difficult type, a frightful old snob he is, and as vain as a peacock. Police investigation will undoubtedly stimulate all his worst qualities. He’s the sort of man who’d go to any lengths to avoid the wrong kind of publicity. We’ll have to go warily if we don’t want him to make fools of us and a confounded nuisance of himself.’

On the way to Marsdon House they went over Davidson’s evidence.

‘It’s a rum thing, when you come to think of it,’ ruminated Fox. ‘There was Sir Daniel looking at that taxi and wishing it wasn’t booked and there inside it were Lord Robert and the man who had made up his mind to kill him. He must have started in to do it almost at once. He hadn’t got much time, after all.’

‘No,’ said Alleyn, ‘the time factor is important.’

‘How exactly d’you reckon he set about it, sir?’

‘I imagine them sitting side by side. The murderer takes out his cigarette-case, if indeed it was a cigarette-case. Perhaps he says something to make Lord Robert lean forward and look through the window. He draws back his hand and hits Lord Robert sharply on the temple with the edge and point of the case—the wound seems to indicate that. Lord Robert slumps back. The murderer presses his muffled hand over the nose and mouth, not too hard but carefully. As the mouth opens he pushes the material he is using between the teeth and further and further back towards the throat. With his other hand he keeps the nostrils closed. And so he sits until they are nearly at Cheyne Walk. When he removes his hands the pulse is still, there is no attempt at respiration. The head falls sideways and he knows it is all over.’ Alleyn clenched his hands. ‘He might have been saved even then, Fox. Artificial respiration might have saved him. But there was the rest of the drive to Queens Gate and then on to the Yard. Hopeless!’

‘The interview with Sir Herbert Carrados ought to clear up this business of Dimitri,’ Fox said. ‘If Sir Herbert was any length of time in the buffet with Dimitri.’