Piggy French ensured that Britain reigned supreme after day one of London 2012's opening Olympic Test Event.

The Norfolk-born rider was greeted by London Olympics chief Sebastian Coe after delivering an outstanding dressage display on DHI Topper W, continued in her rich vein of form.

The 2009 European silver medalist and Badminton runner-up behind legendary New Zealand horseman Mark Todd 10 weeks ago, heads into today's cross-country phase in Greenwich Park with a commanding lead.

Her score of 34.7 penalties put her more than six clear of British-based Australian Clayton Fredericks, with Germany's reigning world champion Michael Jung third. French's British team-mate Pippa Funnell lay fourth with Billy Shannon on 44.1, while the third Team GB member – world number two William Fox-Pitt – was also well-placed aboard Gaucho, a further 2.6 penalties adrift.

The test event, a first competition in the London Prepares series, offers 40 riders from 23 countries the chance to assess the terrain they will tackle for medals next summer.

Around 9,000 tickets across the three days have been distributed via Greenwich Council and the British Equestrian Federation.

Dressage and showjumping take place in an elevated arena constructed on a 5,000 square metre platform designed to avoid damaging the turf beneath it, while today's cross-country will incorporate part of next year's Olympic course.

French underlined her rich potential as a major Olympics medal contender in just over 12 months' time.

'He's a very good horse and I am very excited about him,'' she said. 'Having the chance to be at a competition like this will do him the world of good.

'That was the best dressage test he has been done by a long way. He has come on another level, which you need to do if you are going to be a horse with a shout for next year.

'I will try to enjoy it while it lasts. You know with horses that the next minute you can be flat on your backside rolling around in the dirt somewhere. I am very lucky – I have got some lovely horses.

'Turning to your right during the dressage test and seeing the view (of Canary Wharf's skyline) is surreal. You think you could be in a movie or something, but it's happening. The place has a real buzz about it already, and this is just the test competition. Everyone is very excited.''

• Members of NOGOE (No to Greenwich Olympic Equestrian Events) assembled outside the park's Queen Mary's Gate to protest that the park is not a suitable venue for the 2012 Olympic equestrian events.

Part of the Greenwich World Heritage Site, it is home to many historic buildings, including the Royal Observatory, Royal Naval College and National Maritime Museum.