Zara Phillips, one of two members of the royal family christened to be different from the rest of the House of Windsor, turns out to excel in the one area where her mother, the Princess Royal, and her father, Captain Mark Phillips, were among the world’s most competitive people — in the saddle.

Barring accidents, which come with the territory, Zara’s elevation to the team of riders to defend Britain’s European three-day event title will occur at Blenheim, Oxfordshire, on September 8. At 24 she is the youngest by far to represent Team GB in a sport that is the most demanding and dangerous in her field and on a team where her colleagues are world and Olympic medallists.

She was born to her new role and schooled by the best of British, and German, Australian and Swedish tutors. Yet there is a streak of independence in Zara that is reminiscent of her mother. It has always been on show. Her tabloid nickname for years has been the “royal rebel”, although her rebellions were scarcely worth a stay in the Tower.

There was the tongue piercing, the more recent peroxide hairdo, the “auctioning” of herself for charity to a New Zealand baker so that he could have his own royal PA-for-a-day, and the live-in boyfriends (first Richard Johnson, the top jockey, now Mike Tindall, the England rugby ace). And, of course, there are the partying and the cutting-edge — and often daringly revealing — clothes.

And it shows itself in the way she approaches a sport designed to test the mettle of cavalry officers: dressage to show harmony and precision; a cross-country ride over four miles and devilish fences; and a show-jumping round that comes — if the horse is still deemed sound — on day three.

Master those three disciplines and you are the complete rider. Compete at this level and you prove that you can live at the top of a sport that requires the co-operation of two minds — human and equine — to the limits of nerve and heart and sinew. Expect a favour from an animal because of your background or breeding and you literally come a cropper.

It was why Anne did it: to live on the edge, irrespective of her family circle. It was why the Queen’s daughter met and married Phillips, who had the most enviable way with horses and who to this day coaches the American three-day event riders.

So perhaps it was inevitable that their daughter, who they never wanted to be a princess (just as they did not want her brother Peter to be a prince), was drawn to eventing. “I don’t want to do what they did,” Zara says with mock admonishment when I suggest that she is inspired to follow in their footsteps. She pauses, looks at you with direct blue-grey eyes and adds: “I want to do better than them.”

We are not alone as we talk. Zara’s stipulation, guided by Buckingham Palace and her parents, was that her team-mates — Leslie Law, William Fox-Pitt and Jeanette Brakewell — be included.

We meet at Waresley Park Stud near the Bedfordshire-Cambridge border, the regular home for GB event team training.

When it comes to equestrian competition, Britain is very, very good. We are the European champions. We perpetually vie with the French, Germans, Australians, Americans and New Zealanders for world supremacy. We hold the Olympic gold medal through Law and the team silver from Athens.

Zara, the new recruit, mixes easily with “the oldies” and the other young bloods in the GB squad: Kitty Boggis, Matthew Wright and Oliver Townend, all 23. Wright and Townend will ride as individual British entrants at Blenheim.

The other three are as much born to the saddle as the Queen’s granddaughter. Although nobody can deny that having a “royal” among the riders is added cachet for the sport, it is unthinkable that team selection could be done on anything other than merit. Sit with them and you could not fail to sense a new core — tough, professional, confident, almost irreverent.