Nor must you lead them to feel that the United Kingdom is in any way prepared to assist them in whatever projects they have in mind, morally, physically, officially or unofficially. You must not even let them infer that such is the case, from anything you say; and if you think that despite your caution they have so inferred, then you must negate it.' He studied Merrick in silence for a bit. 'Is that perfectly understood?'

'Yes, sir.'

We went down towards the Serpentine and got snarled up twice in a pack of traffic while I listened to Egerton briefing him: paramount importance of security, limited and circumspect use of protected communications, attitude if apprehended, so forth.

'Their methods of interrogation, as you know, are less charitable than in the West. You must therefore avoid any risk of their taking you into custody, as far as is possible. You will have Mr Longstreet in support, of course, but don't allow your benefit of his greater experience to minimise, in your mind, the real hazards you'll be exposed to.'

Merrick was quite good, sitting to attention on the tip-up and never looking away from the dark glasses even when the taxi gave a lurch. He'd heard all this from the instructors and Egerton knew that but he wanted to tell the boy himself, frighten him with the soft-gloved phrases that would bring his imagination into play instead of blunting it with over-explicitness. The slightly magnified blue eyes held steady as he listened.

Northwards from Hyde Park Corner we found a clear run and got up speed for fifty yards before a double-decker blocked us off again. Baronet — with the Tip that Filters Everything but the Flavour.

'No after effects?' Egerton was asking.

'No, sir.'

I spoke for the first time. 'What was it, exactly?'

Merrick looked at me and then quickly away. 'I slipped on the snow, and a tram nearly got me.'

'Warsaw?’