Clarke receives call-up in maths class.

Brendan Clarke, a Year 12 student at St Francis College in Brisbane, Australia, received the shock invitation on Tuesday to join Jeff Hardwick's Shell Advance Honda team as a replacement for Chris Walker at this weekends German Grand Prix, after the Englishman was controversially dropped.

"I got the call in the middle of maths class," said the excited 18-year-old. "Ever since I saw Wayne Gardner racing when I was four or five, I wanted to be a World 500 Champion.

"We had plans to go over to Europe later in the year to see a Grand Prix but I didn't think I would be racing in one this soon."

Clarke will race a Shell Advance factory-kitted Honda NSR500 V-twin that produces more than three times the horsepower of his production Aprilia, which he raced to victory in this years Aprilia RS250 Challenge.

The Honda V-twin Clarke will be riding is actually Leon Haslam's machine - the Englishman will now make the switch to Walkers vacant, and more powerful, V-four.

"It will be the most powerful and the lightest bike I have ever raced so it will be a step up and a great challenge," Clarke said. "If I can finish amongst the leading V-twins, I'll be happy. It might be a bit weird to see the likes of Rossi, Biaggi and Capirossi on the track with me, but I'll try to slip in behind and stick with them for as long as I can."

Clarke dominated this year's production-based Aprilia RS250 Challenge, winning 16 of the 20 races and setting lap records at each of the five rounds.

"We all thought Brendan would go on to bigger and better things," said George Katrivesis, national manager of John Sample Automotive, Australian importers of Aprilia motorcycles. "However, to have the opportunity to compete in the 500 world championship so quickly is an incredible achievement."

Clarke has flown to Germany with his sponsor and mentor, former Australian Endurance Motorcycle Champion and Brisbane Aprilia dealer, Tony Armstrong.

"In the two years he has been riding in Australia, he has never crashed," said Armstrong. "He has never even bent a lever. The only crash he has ever had was in the United States in July last year when he went over to race in an Aprilia 250 Challenge race. Even that came after he had secured pole and was leading the race by more than three seconds."

The Australian Aprilia RS250 Challenge was established in 2000 to nurture local talent.

Clarke joins a long list of 250cc production riders who have gone on to race in Grand Prix including Mick Doohan, Troy Corser, Garry McCoy, Troy Bayliss and Mat Mladin - making the class a true breeding ground of motorcycling stars.