‘I think I might like that. But wait a moment, sir. I’ve just thought of something … someone, rather. If, as you say you fear, it’s a case of “hunt the woman”, there’s a man I know who might be of assistance.’ She took a small leather wallet from her bag and selected a calling card from it. ‘Can you ring the number you see on there and ask for this person? With a bit of luck he’ll be still at his desk. Unless he’s headed for Claridges already. And, believe me, with the particular task we have on our hands tonight, he’ll be more use to us than a squadron of secret servicemen. He owes me a favour sir. Rather a large one. Just mention my name. He’ll come.’

Joe held the card between finger and thumb with mock distaste. ‘Oh, him! He’d be there like a shot if invited. But what on earth do you imagine this scoundrel could add to the party? A man of his profession? Jackals! The whole lot of them are banned from the hotel. I remember giving the order myself.’

‘He has a very particular skill, sir. The man’s a walking Debrett. Duchesses invite him to their shindigs to enjoy his latest gossip. He knows everyone in society. If there’s someone at the dance tonight who ought not to be there … an infiltrator … a female infiltrator, as you say your information specifies … I can think of no one more likely to spot her. He knows all the usual royal dancing partners. He can list every girl whose waist the prince has ever squeezed in public since he left naval college.’

Joe followed her reasoning and saw the advantages at once. His eyes gleamed as he reached for the telephone. ‘Operator, get me an outside line, would you? It’s a Fleet Street number.’ He read it out and then handed the equipment to Lily. ‘Who’s he working for now, your chap? The Daily Dirt? The Fortnightly Filth?’

‘Hello. Is Cyril there? Good. Fetch him to the phone, will you? Tell him his woman policeman wants him and it’s urgent.’

Joe eyed her with amused speculation while they waited. ‘Been moonlighting, have we, Wentworth? Offering special police services to the gentlemen of the press? Sort of thing I’m supposed to be clamping down on.’

‘Don’t ask, sir. Reputations would suffer. Ah, there you are! Lily here. Lily Wentworth. Yes — too long! Now listen. I’m in a position to do you another favour. How’d you like to be given an exclusive invitation to attend, as a reporter, the Russian knees-up at Claridges tonight?’ Lily winced and held the earpiece an inch away until the surge of exclamations and questions receded.

Impatiently, Joe snatched the phone back. ‘Calm down, man! Cyril Tate? Is that who I’ve got? This is Miss Wentworth’s commanding officer and I’m the one who issues the invitations. Sandilands … I believe we’ve met …Yes, that Sandilands … Feeling’s mutual …Your name’s been mentioned. I have a proposal to put to you. Got the tools of your trade to hand, have you? Can you climb into an evening suit at a moment’s notice?’ In an aside to Lily: ‘He’s already dressed.

‘That’s convenient. Look, meet me and Miss Wentworth in the snug bar of the Red Lion. Yes, just by the Yard in Scotland Alley. Don’t make a fuss! In fifteen minutes.’

He put the phone down.