Funnell was hoping to secure a place in the five-strong Great Britain team for London, but those hopes have now been dashed.

The 43-year-old won team and individual medals at the Sydney and Athens Olympics and is a former European individual champion.

Funnell is also the only rider in eventing history to land the Rolex Grand Slam, eventing's biggest prize awarded for claiming consecutive wins at major four-star events at Kentucky, Badminton and Burghley.

"I am of course devastated that I will not have a horse for London 2012," Funnell said. "Winning a medal at London would have been the pinnacle of my career.

"I also feel so disappointed and upset for my loyal owners and hard-working grooms and other support staff. London was their dream too.

"Disappointment is part and parcel of equine sport. Perhaps that is why the successes are so sweet.

"I wish all the British riders the best of luck and I hope they bring home a bucket full of medals."

Disappointing

William Fox-Pitt, the current world number one, Mary King, Piggy French and Nicola Wilson are expected to fill four of the British places at London.

Funnell would probably have been challenging for a spot alongside the likes of Tina Cook, Oliver Townend, Laura Collett, Lucy Wiegersma and possibly Zara Phillips.

"It is disappointing that we will not have a rider of Pippa's calibre contending selection for London," British eventing performance manager Yogi Breisner said.

"Pippa, supported by her owners, has worked very hard to bring both of these horses up to a standard where they would have been in contention for selection.

"I feel very disappointed for Pippa, who is a professional in all she does. She is a pleasure to work with and a great team member."