Elizabeth feels strangely detached from herself but still hyper aware of everything: the warm, smooth weight of the pearls at her throat; the prickle of the crystals on her skirt where her hands rest under the bouquet of flowers whose scent mingles with the faintly musty smell of the old leather seats; the mesmerising sway of the elderly carriage.

The journey is a sensory blur, so much so that she is almost disorientated when the coach stops outside Westminster Abbey. A footman opens the door, her father descends first, and turns to help her out. A team of assistants materialise to lift the train carefully out of the carriage after her and twitch it into position.

Margaret and the other bridesmaids are waiting for her, smiling, with her two little pageboys in kilts, Prince William of Kent and Prince Michael of Gloucester. As Elizabeth and the King arrive, the bridesmaids dip into curtseys in a rustling blur of organdie.

A final adjustment to the veil, and her father holds out his arm. ‘Ready?’

She swallows. ‘Ready.’

There is a moment of absolute silence as they stand framed in the ancient doorway, both momentarily blinded by the blaze of colour and light ahead of the them. Under its soaring ceiling and arches, the abbey is crammed with guests in a multitude of costumes: there are turbans and chasubles, sheikh’s robes and surplices, red and blue uniforms decked with gleaming medals, gorgeous dresses and a plethora of diamonds, rubies, emeralds, and sapphires, all winking and glittering in the ceiling lights.

But she can’t see Philip. A red carpet stretches the length of the nave, into the distance. To Elizabeth, standing dazzled in the doorway, the altar seems twice as far as in the rehearsal but somewhere up there he will be waiting for her.

When we’re standing there at the altar, it’ll be just you and me.

Ahead of the King, the Royal Standard is ceremonially dipped to the floor. This is her cue. Out of nowhere, Elizabeth remembers the dizzying fear of waiting to go on stage in the Waterloo Chamber all those years ago. She remembers peeking through the curtains to see if Philip had arrived and the bitterness of her disappointment at realising he wasn’t there.

The memory makes her hesitate and then she forces herself to step forward to a tremendous roll of drums and a heart-shaking trumpet voluntary that resounds in the great cathedral.

There is a momentary jolt as one of her pageboys – William, she thinks – gets flustered and treads on her train. Someone hisses at him to get off, and she can move forward again, walking slowly up the long, long aisle with her father beside her. The congregation rustles into bows and curtseys as they pass while the choristers’ voices soar over the sonorous sound of the organ.

And then Philip steps out and turns to watch her coming towards him, and Elizabeth forgets the pageboys, forgets the guests. Forgets that millions are listening on the wireless or watching on television or waiting outside.