‘Oh yes, she did, sir! She gave me the name of the woman who tried to poison the prince and told me where she was living. I went straight round there – oh, I know, disobeying orders, and I expect you’ll be angry with me, but it was on my way back …’

‘Get on, constable!’

‘Well, she made fools of Bacchus and his Keystone Kops, but I’ve got her, sir!’

Joe looked anxiously at the door. ‘Got her? Lord! You’ve not left a body down at reception, Wentworth? What on earth have you done?’

‘Oh, nothing like that! No fisticuffs. But I did some detecting. I know what she looks like, I know who she is and I can guess where she is but I can’t for the life of me work out why this woman would want the prince dead. Or Admiral Lord Dedham or Churchill or Lloyd George. Perhaps you’ll be able to tell me?’

‘Wentworth, start at the beginning. You got there …’

Joe listened patiently to Lily’s account, making occasional notes of names and other details that caught his attention.

‘And you’d describe the princess’s manner as – helpful – on the whole?’

‘On the whole, sir. And on the surface. No more than that. I wouldn’t trust her as far as the garden gate.’

‘Aha! Let’s think of her as “Princess Rat”! Go on, Wentworth.’

‘She doesn’t like us much. She has strong views on the political situation and, though grateful to this country for the shelter she’s receiving, doesn’t scruple to voice her criticisms. But she would never, I think, condone the assassination of the prince or cover for any would-be assassin. Her community of refugees has too much to lose. It would be a suicidal idiot who stove a hole in the lifeboat he was travelling in. And she has much loyalty to the notion of kingship, which seems in that company to trump nationality. Or even friendship.’ Lily paused for a moment and then added: ‘She’s a politician. She weighed her options and in the end she decided to give her up. Your Morrigan. But on her terms. Not ours. Oh, no, not ours.’

‘In what way did she “give her up”?’

‘She handed me the name of a woman who might well have been at the ball as a guest but was, in fact, working in the kitchens. No surprises! It’s the girl I saw smearing the prince’s plate. She’s Anna Petrovna, and she’s related to the princess. She was living just a short distance away, but in a much less grand district. In fact just across the road from the address Bacchus raided. She was watching his antics from behind the net curtain of her upstairs front. I thought I’d just check on it on my way back here … I hadn’t at that time realized I too was being deliberately sent off on a wild goose chase. These Russian women are making monkeys of us, sir.’

‘It’s how they pass their time, Wentworth. I wish they’d take up needlepoint but they find espionage more stimulating. So, you’re reporting that Miss Petrovna is gadding about London, free as the wind. You haven’t got her at all, any more than Bacchus had. Or Hopkirk. A stroll across the allotments and the whole of the West End is at her feet.’

‘No, sir! I know exactly where she is. I must have been within a few yards of her this morning. She was listening to what I was saying through a keyhole for all I know.’ Lily shivered.

‘Keyhole? Whose keyhole?’ he asked with suspicion. And then with sudden alarm: ‘Oh, my God! She was there? Within a few feet of you? What makes you think so?’

‘The coffee cups. A tray arrived moments after I did. It was laid for four. The maid who brought it was surprised to see me and asked if she should bring another cup. Which would have made it five. One too many. She was hurried out of the room. There had been four women there when I arrived, not the three who greeted me. Anna must have skipped out when I rang the doorbell. The coffee cups had no significance for me at that moment but it hit me later. The princess was pleased and relieved to be able to get me off the premises by sending me along to Hogsmire Lane. The gesture made her appear cooperative to the police but she was giving nothing away as she knew perfectly well that the address had already been abandoned. She – and possibly the whole of the Russian establishment – is sheltering this woman. You’re going to find that a hard nut to crack, I think.’

‘Wentworth, we are not unaware of this. The princess and her entourage have been the subject of close surveillance ever since she moved to London. She knows it, of course. Clandestine manoeuvring is meat and drink to her. She’s at the heart of a network that has tentacles covering the world and she works tirelessly for her own kind: émigré Russian aristocrats. She has a finger in every ambassadorial pie from here to Hong Kong and back again the other way.’

‘I’ve just remembered – they were about to set off for lunch at the embassy. They could have taken Anna along with them and …’

‘And left her there. On what is technically foreign territory. If she stays holed up in the embassy, we can’t touch her. They could spirit her out of the country in a bag in no time. But I think she was pulling the wool over your eyes. Which embassy, for a start? Did she say? That part of town is an international diplomatic enclave. You can’t throw a stone without knocking off an ambassador’s silk hat. And with the political situation as it is at the moment in that benighted country Miss Petrovna would be the very last person the present Russian mob would want to see come grinning round the door. We’re not contemplating the usual diplomatic protocol – these are bloodletting rogues and scoundrels we have to deal with. No idea how to behave on a world stage. They might approach our government and ask to have her removed.’ Joe sighed. ‘With the usual vociferous complaints about Scotland Yard intimidation and mismanagement. Whatever happens, I think we could be looking at diplomatic involvement. The quickest way to wreck a career. Damn!’

‘Sorry, sir. If I’d caught on straight away I could have rung you from the princess’s house …’ Her voice trailed away and she hung her head, waiting for a rebuke.

He smiled. ‘… and requested a snatch squad? “Come quickly! She’s hiding in the butler’s pantry!” I can’t quite see how that would have worked.’

‘No. They’d never have got past Foxton, sir.’

‘Well, cheer up. You’ve done wonders. I’m very pleased, Miss Wentworth.’ He sat back, eyeing her with satisfaction. ‘Would you like to hear me ruin someone’s lunch?’ He picked up the telephone and asked for a London number. ‘Have I got Bacchus? James! Listen. You may wish to reschedule your surveillance in the light of certain information which comes to hand. Your girl was watching your storming of forty-two, Hogsmire Lane from her outpost in the upstairs front room of number sixty-seven … yes, I said sixty-seven … which was her actual address. No … not there any longer. Clean pair of heels over the allotments at the rear… She’s taken shelter with her countrymen. She was playing cards with the Princess Ratziatinsky when Wentworth called this morning. Yes. Wentworth has been entrusted with the girl’s details … things like real name, character, possible motive, that sort of thing … By all means. I’m sure she’ll be glad to update your information.’

Joe held the earpiece at an exaggerated distance from his ear and grimaced. ‘That’s got him going. He’ll burst a blood vessel trying to keep up now. I wouldn’t want to be one of his chaps.’

‘And you’ve just killed off any chance of my ever gaining Bacchus’s confidence, sir,’ she murmured.

‘No harm done. That was dead in the water anyway. You’re never going to be soulmates. In any case, I doubt the chap has a soul.’

‘Poor Bacchus! No mother and now no soul? I can begin to feel sorry for him.’

‘Waste of time. I’ll try to keep you off his back. Best I can offer.’

He watched as the girl shrugged and conceded a bleak smile. He thought he’d try for a warmer one. He’d been a bit hard on her, perhaps. ‘And now … reward for a jolly good morning’s work! I’m going to say a few words that may produce a reaction. Are you ready?’ He gave her the benefit of his most seductive tone. ‘What about roast beef … Yorkshire pudding … horseradish sauce … apple charlotte …’