The Westhamptons’ house party was one of several in Cambridgeshire held to coincide with May Week. The guests included Earl Fitzherbert, known as Fitz, and his wife, Bea. She was Countess Fitzherbert, of course, but she preferred her Russian title of Princess. Their elder son, Boy, was at Trinity College.

Princess Bea was one of the social matriarchs who were doubtful about Daisy. Without actually telling a lie, Daisy had let people assume that her father was a Russian nobleman who had lost everything in the revolution, rather than a factory worker who had fled to America one step ahead of the police. But Bea was not taken in. ‘I can’t recall a family called Peshkov in St Petersburg or Moscow,’ she had said, hardly pretending to be puzzled; and Daisy had forced herself to smile as if it was of no consequence what the princess could remember.

There were three girls the same age as Daisy and Eva: the Westhampton twins plus May Murray, the daughter of a general. The balls went on all night, so everyone slept until midday, but the afternoons were dull. The five girls lazed in the garden or strolled in the woods. Now, sitting up in her hammock, Daisy said: ‘What can you do after you’re engaged?’

Lindy said: ‘You can rub his thing.’

‘Until it squirts,’ said her sister.

May Murray, who was not as daring as the twins, said: ‘Oh, disgusting!’

That only encouraged the twins. ‘Or you can suck it,’ said Lindy. ‘They like that best of all.’

‘Stop it!’ May protested. ‘You’re just making this up.’

They stopped, having teased May enough. ‘I’m bored,’ said Lindy. ‘What shall we do?’

An imp of mischief seized Daisy, and she said: ‘Let’s come down to dinner in men’s clothes.’

She regretted it immediately. A stunt like that could ruin her social career when it had only just got started.

Eva’s German sense of propriety was upset. ‘Daisy, you don’t mean it!’

‘No,’ she said. ‘Silly notion.’

The twins had their mother’s fine blonde hair, not their father’s dark curls, but they had inherited his streak of naughtiness, and they both loved the idea. ‘They’ll all be in tailcoats tonight, so we can steal their dinner jackets,’ said Lindy.

‘Yes!’ said her twin. ‘We’ll do it while they’re having tea.’

Daisy saw that it was too late to back out.

May Murray said: ‘We couldn’t go to the ball like that!’ The whole party was to attend the Trinity Ball after dinner.

‘We’ll change again before leaving,’ said Lizzie.

May was a timid creature, probably cowed by her military father, and she always went along with whatever the other girls decided. Eva as the only dissident was overruled, and the plan went ahead.

When the time came to dress for dinner, a maid brought two evening suits into the bedroom Daisy was sharing with Eva. The maid’s name was Ruby. Yesterday she had been miserable with toothache, so Daisy had given her the money for a dentist, and she had had the tooth pulled out. Now Ruby was bright-eyed with excitement, toothache forgotten. ‘Here you are, ladies!’ she said. ‘Sir Bartholomew’s should be small enough for you, Miss Peshkov, and Mr Andrew Fitzherbert’s for Miss Rothmann.’