She took a trinket box from a table, opened it and produced a diamond brooch. ‘The fool tried to give this away. To make the correct impression, no doubt. I knew it was Zinia’s much-loved jewel that she had from her mother. It would not have been offered for charity with her consent. I arranged for a friend to make a discreet bid and I acquired it. Zinia shall have it back. And the support to start a new life. In Paris perhaps. I think Paris will be good for her. Whether Zinia will be good for Paris is less certain. And now you may tell me why you have come to see me.’

Lily responded with equal succinctness. Her request for the original guest list was received with no more than the slightest lift of an eyebrow and the princess moved at once to an escritoire. She took a sheet or two of foolscap paper from a drawer, looked over them briefly and brought them to Lily.

‘I’ll hover at your shoulder,’ she said. ‘The handwriting is my own and difficult to decipher. Can you tell me for whom you are searching?’

‘I’m looking for a name which is here on your first list but not on the lists the Branch men made of arrivals at the ball.’ Lily took two sheets from her handbag. ‘Here’s the cast in order of appearance. And here’s another list, with superb efficiency, giving the same names in alphabetical order.’

The princess sighed. ‘Two hundred names to consider! But you were right to come to me. I can shorten the task, I believe. The evening was very well attended. It was the society event of the year in the highest circles and there were few indeed who failed to make an appearance. And I am aware of all of them. Two gentlemen, two ladies. Now … the Duke and Duchess of Sunderland … here they are, you see, on my list … did not attend. Elderly couple. He fell off his horse last week and is confined to his estate. Here we have Miss Millicent Gregory (Ludmilla Gregorovich back home in Russia) who found herself unavoidably detained in Paris.’ The princess sniffed her disapproval.

‘By an Italian tenor?’ Lily enquired sympathetically, remembering her aunt’s list.

‘You have it,’ said the princess. ‘My word! The Yard is all-knowing.’

‘Can you describe Miss Gregory?’

‘Pretty as a peony, with half the intelligence. Wet as a worm.’ She paused for a moment. ‘Ludmilla couldn’t brew up a cup of tea let alone administer a dose of cyanide. If it’s a poisoner you’re looking for in the cracks in these lists, she’s not the one.’

A beringed finger pointed to a name near the end of the page. ‘And, lastly, here you see the Spanish envoy to the Court of St James. Ah, now there’s a handsome villain! He could kill anyone. He’s cut a swathe through Europe. Those that don’t fall to his charm fall to his knife. I was looking forward to meeting him. But he was envoyed back home last week for bad behaviour more blatant than usual. Can you tell me more precisely what you have in mind?’

‘As you suppose, we’re looking for the man or woman who poisoned Gustavus, by design or by mistake.’

‘But you fear the Prince of Wales was the target? My dear Lily, you’ve taken leave of your senses. Your prince was never in danger. He was among friends and subjects. He could have raised a squadron of admirers and protectors amongst this company – there was no safer place in England for him to spend the evening. He was as safe as the Pope surrounded by his Swiss Guard! And Edward knew that. That is why, against all advice from your secret services, he felt able to accept the invitation. No – whoever the assassin, I would say he got his man. Though I could wish he hadn’t chosen my party as the scene of his crime. Aren’t there dark alleys enough in London? So inconsiderate!’ The princess gave a grating laugh. ‘Mais, quand même – good luck to him!’

‘I think it’s in the ancient nature of the assassin to choose a public stage for his coup, isn’t it?’ Lily suggested. ‘And your glittering event would have provided him with an unforgettable backdrop for his effort.’

‘Yes, the hashashin! You’re right. They liked an audience for their dramas. And still do in the modern world. So many men shot and hacked to death in theatres, in arenas, in the course of parades! If one were very naive, one might almost suspect an international conspiracy.’

Lily felt a keen mind at work in the sophisticated woman she was taking into her confidence and decided to press her further. ‘Your Highness, we’re seeking not a man but a woman, and a woman who may have a connection with the political ambitions, not of your country, but of another.’

‘Great heavens! But by whom does she feel threatened – the invincible Britannia? Could you be speaking of the Irish? I’ve read in the newspapers that … A Fenian attempt? On poor Edward? Under cover of my party? Oh, I see … How dare they!’ Her outrage swiftly dimmed to foreboding. She shuddered. ‘Surely not? Can it have come to this? Such barbarity! France … Greece … Russia … Continents swept by a tide of red, murderous madmen. Incompetent nihilists! Children who break what they do not understand and are incapable of repairing it. Must England suffer the same fate of death and destruction? I had thought it safe from Vandal hands.’

‘We have other ways – civilized ways – of managing these things in our country,’ was the most neutral comment Lily could come up with.

‘Ah, yes. You have Sandilands and his like.’ The princess nodded. ‘Bastions of law and order. You probably believe that if only there had been a Scotland Yard presence in Sarajevo that day in 1914, a swift arrest would have ensued, the murderer of the archduke would have been instantly popped into the local jail in handcuffs and a convincing and totally consoling cover story put in place. The whole affair dampened down … war avoided … millions of lives saved.’ Her voice was impatient and pitying. ‘I admire your motives but I despair of your naivety. Never! The guns had been manufactured, sold and stockpiled. Armies were standing by, flexing their trigger fingers; commanders were strutting, heads of government were whipping up ancient grievances. The men of Europe were straining for a war. When the will to war is there, one bullet from a madman’s gun outweighs years of diplomacy.’

Lily was silent, her heart and her head with the princess as she plunged on with her denunciation: ‘And perhaps the will to a further war is gathering already? So soon! Your commander has seen this. I admire him but he is no more than a quixotic boy who has blocked a hole in a crumbling sea-wall with his finger.’

These were Lily’s sentiments exactly, so she was surprised to hear herself murmuring: ‘Strong finger, though. What would you have him do? See the danger and selfishly run away from it? That is not in his character. That is not in our tradition.’

A cynical bark of laughter greeted this pious but heartfelt assertion.

‘My dear Lily! You are too much in awe of your cousin and your country. Sandilands is an admirable man but he serves a selfish mistress. Britannia picks and chooses the causes she espouses and completely without sentimentality. When she meddles in the affairs of a foreign nation, it is always in the pursuit of her own interests.’

‘But …’ Lily was struggling with the need for deference and circumspection which Sandilands had impressed upon her when she would have liked to give her hostess a good earwigging. The princess had gone too far. She had dug deep but she had at last found the vein of patriotism that ran through her English guest. Lily wanted to invoke the generous way Russian refugees had been welcomed into the British capital, the way the British army had stood shoulder to shoulder with the Russians against the Germans, the sacrifices made by young men she had known and still remembered, falling in foreign fields for a cause that was not theirs. She murmured her objections, overawed by the older woman’s rank and hobbled by the suspicion that the lady would no doubt be engaged in a telephone conversation with Sandilands the moment Lily had left.