‘If there are any other questions—’ he began.

‘But yes, certainly there is a question. Carlile. Carlile is the question!’

Lord Mayfield’s colour rose a little.

‘Carlile, M. Poirot, is quite above suspicion! He has been my confidential secretary for nine years. He has access to all my private papers, and I may point out to you that he could have made a copy of the plans and a tracing of the specifications quite easily without anyone being the wiser.’

‘I appreciate your point,’ said Poirot. ‘If he had been guilty there would be no need for him to stage a clumsy robbery.’

‘In any case,’ said Lord Mayfield, ‘I am sure of Carlile. I will guarantee him.’

‘Carlile,’ said Carrington gruffly, ‘is all right.’

Poirot spread out his hands gracefully.

‘And this Mrs Vanderlyn—she is all wrong?’

‘She’s a wrong ’un all right,’ said Sir George.

Lord Mayfield said in more measured tones:

‘I think, M. Poirot, that there can be no doubt of Mrs Vanderlyn’s—well—activities. The Foreign Office can give you more precious data as to that.’

‘And the maid, you take it, is in with her mistress?’

‘Not a doubt of it,’ said Sir George.

‘It seems to me a plausible assumption,’ said Lord Mayfield more cautiously.

There was a pause. Poirot sighed, and absent-mindedly rearranged one or two articles on a table at his right hand. Then he said:

‘I take it that these papers represented money? That is, the stolen papers would be definitely worth a large sum in cash.’

‘If presented in a certain quarter—yes.’

‘Such as?’

Sir George mentioned the names of two European powers.

Poirot nodded.

‘That fact would be known to anyone, I take it?’

‘Mrs Vanderlyn would know it all right.’

‘I said to anyone?’

‘I suppose so, yes.’

‘Anyone with a minimum of intelligence would appreciate the cash value of the plans?’

‘Yes, but M. Poirot—’ Lord Mayfield was looking rather uncomfortable.

Poirot held up a hand.

‘I do what you call explore all the avenues.’

Suddenly he rose again, stepped nimbly out of the window and with a flashlight examined the edge of the grass at the farther side of the terrace.

The two men watched him.

He came in again, sat down and said:

‘Tell me, Lord Mayfield, this malefactor, this skulker in the shadows, you do not have him pursued?’

Lord Mayfield shrugged his shoulders.

‘At the bottom of the garden he could make his way out to a main road. If he had a car waiting there, he would soon be out of reach—’

‘But there are the police—the A.A. scouts—’

Sir George interrupted.

‘You forget, M. Poirot. We cannot risk publicity. If it were to get out that these plans had been stolen, the result would be extremely unfavourable to the Party.’

‘Ah, yes,’ said Poirot. ‘One must remember La Politique. The great discretion must be observed. You send instead for me. Ah well, perhaps it is simpler.’

‘You are hopeful of success, M. Poirot?’ Lord Mayfield sounded a trifle incredulous.