Then the cabinet and mirror that disguise the door are swung open and they step into the noise and brilliance of the drawing room. Beneath the great chandelier, the room is a kaleidoscope of vividly coloured gowns while the animated conversation bounces off the gilded walls. Elizabeth and Philip move together among the guests, accepting congratulations as they go.

For Elizabeth, it is as if all her senses are on high alert. Usually she is tense, concentrating fiercely on making conversation, but today, with Philip at her side, she is acutely aware of her body, of the way her dress rustles as she moves, of the warm weight of the pearls at her throat, the gleam of diamonds on her finger. And most of all, of Philip beside her, tall and proud in his shabby naval uniform.

As always, it strikes Elizabeth that he carries his own forcefield around with him. It makes everyone else dim in comparison to his vivid presence. He is not smooth or polished, but it is impossible not to take note of him. Whenever Elizabeth feels her shyness struggling back to the surface, she glances at him, and it is almost as if she has reached out and touched him. She doesn’t, but he always knows exactly when to turn his head and meet her eyes with the merest flicker of a reassuring wink that makes her pulse jolt.

Her mother is standing with Philip’s lively cousin, Sandra, and her husband, King Peter of Yugoslavia, when Elizabeth and Philip make their way round to them.

‘So many congratulations,’ Sandra says, kissing Philip. ‘You’ve come a long way since you let those pigs out at Panker,’ she tells him. She turns to Elizabeth and the Queen. ‘Philip was such a naughty boy,’ she says. ‘There was a model farm there and we were fascinated by the pigs. It was Philip’s idea to stir them up and unbolt the stalls. The next thing we knew there was pandemonium, with pigs stampeding all over the tea lawn. Tea things all over the grass, tables turned over, aunts and uncles screaming and shouting …’ She laughs merrily. ‘Oh, it was fun while it lasted, wasn’t it, Philip?’

‘I don’t remember anything about it,’ Philip says.

‘You must do!’

‘I’m quite prepared to believe that I was a little devil, but I’ve got absolutely no recollection of squealing pigs on the tea lawn.’

‘Talking of tea lawns,’ the Queen interrupts smoothly before it descends into a cousinly squabble, ‘there is a garden party here tomorrow, and the King and I think it would be a good idea if you came, Philip. It would be a good opportunity for you and Lilibet to appear together in public for the first time.’

Elizabeth sees Philip resist the temptation to grimace. ‘Of course,’ he says.

Peter winks at him. ‘I see they’re wasting no time throwing you to the lions, Philip!’

‘Peter!’ the Queen protests. ‘It’s just a garden party! Philip will have to learn that’s part of the job.’