‘Look, Rosa,’ said Ruth. As Nancy and Rosa looked up, Ruth grabbed a broom from its prop on the wall. Then, holding it as tight as a lover, she twirled across the empty ballroom floor. It was a simple two-step, the sort anyone who’d ever been to a dance hall might dance, but she put her own flourishes in, rocking the broom back and forth as if it was swooning in her arms. ‘Madam!’ she declared, in a perfect imitation of the King’s English.

Rosa spluttered all over the chandelier clasp she had been polishing. ‘Give over, would you? If Mrs Moffatt comes back . . .’

But Ruth continued twirling around, dancing some wanton tango up and down the ballroom floor. On the other side, one of the carpenters elbowed his workmate in the side and cried out, ‘Here’s Hélène Marchmont herself!’

Rosa whispered, ‘I’d give anything to be Hélène Marchmont and have Raymond de Guise all to myself . . .’

Nancy’s eyes shot up. ‘Hélène Marchmont . . . and Raymond de Guise?’

‘Well, it stands to reason, doesn’t it? Two folks as beautiful as them. Bound to happen, isn’t it? They hold each other almost every night anyway. And do you think you can dance with someone like that if you’re not a little bit in love?’

‘I don’t know,’ chipped in Ruth. ‘Raymond de Guise hardly ever leaves the Buckingham. Not unless it’s to one of those tea parties, or he’s invited to some toff’s wedding. But Hélène Marchmont? Now, that’s different. She’s off, out of here, every chance she gets! Like she’s got somewhere better to be.’

‘Double life,’ said Rosa. ‘She’s probably lead dancer at the Imperial. Choreographer at the Savoy.’

‘Nothing as ordinary!’ Ruth crowed. ‘She’s got a lover somewhere, you mark my words. A lovely doomed affair, like you get in the magazines. Oh, I can just imagine it, can’t you? She jumps in a taxicab every second she gets, and then she’s up in some Bloomsbury mansion or out at some country estate.’

‘Why keep it a secret?’

‘Obvious, isn’t it? She’s somebody’s mistress. Somebody who matters. Well, when you’re as beautiful as Hélène Marchmont, you get to take your pick.’

‘I still say she’s with Raymond de Guise. It’s just too perfect.’

‘Too perfect is right. And, anyway, Lord de Guise hasn’t got time for her. He’s running himself ragged with all the guests. He goes up to their rooms with them, doesn’t he? Not just a dancer, that one . . .’

‘Wh-what do you mean?’ Nancy stammered.