The rider – who turns 21 today – took the historic win riding Glenavadra Brilliant, with whom he also came a very creditable fifth in the Al Shira’aa Derby this year.
Something of a Hickstead specialist, the horse famously won the Al Shira’aa Derby while being campaigned by James’s brother William in 2016.
Only four combinations jumped clear in the first round of the class, and only two of those could repeat that in the jump-off.
Pippa Funnell – Team GBR Olympic event rider and wife of showjumper William – jumped faultlessly with Billy Congo in a time of 54.34 and was on course for the win, until James stopped the clock on 52.97.
Whitaker said: “He loves big grass arenas like this, and he always seems to perform well here. When I saw Pippa go I thought, ‘there’s no way I’m going to beat that’.
“It’s unreal – a dream come true. Winning a class like this was definitely on the bucket list.
“I started riding Glenavadra Brilliant when Will moved to Belgium.
“When we first got him he was just like a tank and you couldn’t turn him. We knew it would just take time.
“He’s a big horse with a long stride and he’s pulling me all the time.
“You have to keep that big, slow rhythm. I went in the jump-off on a wing and a prayer really.”
Part of the famous Whitaker dynasty, James is the son of Ian and Alison, and is following in the footsteps of older brothers William and George ,who also showjump successfully. Since they moved on, James has taken over the yard at which Michael and John grew up and hopes to expand his string of horses.
The Longines FEI Jumping Nations Cup of Great Britain at the BHS Royal International Horse Show, which finished yesterday, is one of the oldest equestrian events in the world, as well as one of the biggest outdoor horse shows in the country.
Showjumping highlights during the five-day event included the Longines FEI Jumping Nations Cup of Great Britain, the Longines BHS King George V Gold Cup, the BHS Queen Elizabeth II Cup and the MS Amlin Eventers’ Challenge.
Great Britain went within touching distance of claiming an odds-defying Nations Cup win at Hickstead’ yesterday.
Despite seeing their top rider –former world No 1 showjumper Scott Brash – eliminated in both rounds, Britain pushed eventual winners Ireland to a jump-off.
In the end Ireland’s Anthony Condon delivered a brilliant performance with SFS Aristio, clocking 41.29 seconds to thwart British jump-off challenger Holly Smith, riding Hearts Destiny.
Britain had not won the Prince of Wales Trophy – Hickstead’s Nations Cup prize – since 2010, and it proved a thrilling battle against the Irish, with Brazil finishng third, Sweden fourth and Belgium fifth.
The Nations Cup European division concludes in Dublin on August 10, when qualification places for this year’s Barcelona Nations Cup final will be confirmed.