The home hope triumphed after an 18-rider jump-off at Olympia to secure the biggest victory of his career at the Western European League competition.

Riding Utamaro D Ecaussines, the 29-year-old went double clear and clocked the quickest jump-off time of 37.02sec.

"It's s surreal," said Whitaker, whose win came at the London Horse Show.

"Since I've been coming here as a kid this has been a dream, and I can't believe it's actually happened."

Nine riders went clear again in the jump-off.

Belgium's Karel Cox clinched second on Evert, stopping the watches at 37.21 second time around.

American Laura Kraut rode Zeremonie to a jump-off time of 37.70 to complete the podium.

"The World Cup at Olympia is like a Championship, you get one shot at it every year and it's all got to come together on the day," Whitaker added. 

"I told myself, 'if you're clear in the first round then don't hold back.'"

All of the Jumping World Cup events around the world serve as qualifiers for the World Cup Final in Swedish city Gothenburg in April.

Switzerland's Steve Guerdat currently tops the Western European League leaderboard on 58 points.

The circuit moves to Mechelen in Belgium next weekend.