TOCKENHAM rider Jessica Mendoza ensured British success on day one of the London Global Champions Tour event at Horse Guards Parade today.
The 18-year-old took the opening five-star class - a two-phase competition - with Ramiro de Belle Vue.
Mendoza is rated among British showjumping's brightest prospects, and she produced a sparkling performance to dominate a 63-strong field.
Mendoza's time of 27.74 seconds delivered a comfortable victory over her closest challenger - reigning European individual champion Roger-Yves Bost, riding Colombo van der Blauwaert - while Britain's Robert Whitaker took third spot on USA Today.
Whitaker, a member of Britain's Nations Cup team at Hickstead earlier this month, also featured prominently in Thursday's feature class, the Maybourne Cup.
The Yorkshireman again finished third, this time aboard Catwalk IV, just in front of Michael Whitaker and Elie van de Kolmen.
More than 20 combinations made the jump-off, which was partially fought out in torrential rain, and first-to-go Beat Mandl set a pace that no other combination could threaten.
The Swiss rider guided Antares F home in a time of 31.67 seconds to take the £16,000 winner's pure, with another Swiss combination - Jane Richard-Phillips and Quister de Guldenbloom - finishing as runner-up.
The action continues on Friday, building towards Saturday's Longines London GCT Grand Prix, which carries a six-figure top prize.
London is the 11th of this season's 14-event GCT series, which ends in Doha in November. British star and current world number one Scott Brash won the overall GCT crown last year.