The 18-year-old bay gelding, ridden by Daisy Berkeley, is believed to have suffered a heart attack just prior to a cross-country fence during an intermediate class yesterday.

Berkeley, who suffered minor cuts and bruises, rode Spring Along at the 2008 Olympics equestrian competition in Hong Kong, where the combination featured in the Great Britain team's bronze medal performance.

They were third at the prestigious Badminton event last year and were also crowned 2010 British Open champions at Gatcombe eight months ago.

In a statement, British Eventing said: "It is with great sadness that we announce that Spring Along, ridden by Daisy Berkeley and owned by Mrs Christine Dick and the rider, died as a result of a fatal accident at fence number 23, a double of steps up, while competing at Gatcombe British Eventing One-Day Event in Gloucestershire.

"Spring Along, an 18-year-old bay gelding, is believed to have had a heart attack just prior to the first step up, so simply fell on top of the first step and found to be dead by the vets when they arrived at the fence.

"Daisy sustained minor cuts and bruises, and was understandably very upset."

He also helped Britain to gold at the 2007 Pratoni European Championships and silver at the World Equestrian Games in Aachen the previous year.