Elizabeth strokes the horse’s nose and they take the measure of each other. The mare, she senses, is afraid that she is in for a sedate ride, and Elizabeth is able to promise her that there will be no holding back. She swings into the saddle, loving the responsive feel of the horse beneath her.

‘Let’s go,’ she says, smiling.

The horses are fresh and they let them have their heads, hooves thundering as they gallop over the veldt. The sky is flushed an unearthly pink, and Elizabeth can smell horse and dry grass and dust as they race towards a lone acacia tree in the distance. She can feel the bunch of the mare’s muscles, the easy power of her stride. For so long she has held herself tight, but in the hush of that African dawn, Elizabeth feels her chest loosen and unlock, and she lets out a whoop of exhilaration.

The mare responds to her excitement and powers ahead, leaving Margaret and Peter behind on their more sluggish mounts. A broad smile on her face, Elizabeth crouches over the horse’s mane, her thighs clamped tight around the saddle, and her hair blown anyhow. She doesn’t care what she looks like: she just wants to gallop forever towards the horizon, faster and further.

When they reach the acacia tree, Elizabeth pulls the horse up reluctantly to rest while Margaret and Peter catch up. Easy in the saddle, she surveys the empty horizon while the mare snorts and tosses her mane, well pleased by the run.

It is like being at sea, Elizabeth thinks. The same space, the same light, the same sense of being untethered. It makes her realise how confined her life has been until now. Oh, there is Balmoral, of course, and Sandringham, but for most of the war she was at Windsor Castle, where the horizon is constantly interrupted by towers or stone walls or shrouded in grey clouds.

There is nothing to break up the emptiness here, just this tree, stark against the great bowl of the sky. Elizabeth can feel herself changing, filling up the space. This trip has been eye-opening for her. She didn’t want to come, didn’t want to leave Philip, but it has been good for her, she can see that now. It has not just been about seeing a new country, interesting though that has been. These weeks with her parents and Margaret have given her a new insight into their family and what it means to be royal.

She has watched her parents and understands now what is expected of them, and what will be expected of her in the future. In particular, Elizabeth has a new appreciation of her mother. The Queen is unfailingly charming. Her smile never falters, no matter how tedious the dinner or how long the reception. She sits through displays of dancing and accepts bouquets with an expression of lively interest. And she always looks immaculate. Her hats are things of beauty, and her shoes designed to boost her height, although they are not always the most practical footwear.