The Royals cheered on Zara as she and her horse, High Kingdom, made their Olympic bow after finishing in 24th place during the event in Greenwich Park yesterday.
Also in attendance was Zara's rugby star husband Mike Tindall who gave his wife a big kiss and took a photograph of her with a London 2012 volunteer afterwards.
But, despite the big smile Phillips later spoke of her disappointment, confessing: 'It was such a big test and I had a couple of mistakes.
'I was so disapointed with the first change because normally he does good changes but, overall, I was pleased with how he dealt with everything.
'There are a lot of people here with it being on home soil so I'm lucky that he doesn't really get too wound up by the crowd- they actually lifted him a bit.
'I was happy with the way he handled it- although he's inexperienced he coped with the crowd well.
'He was pretty chilled but he still has a lot to learn.'
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