Grapevine: Minister quits to focus on Le Mans

Drayson competed in the British GT championship this year, where he finished third in the drivers' standings at the wheel of a bio-ethanol-powered Aston Martin DBRS9 for Barwell Motorsport.

The 47-year-old will compete in the American Le Mans Series next year, as success in that championship is one way of teams gaining at entry for the 24-hour race in June.

In a letter to Prime Minister Gordon Brown, published by the BBC website, Drayson explained that he had a passion for motor racing.

"A number of special circumstances have now presented me with a once-in-a-lifetime opportunity," he said in the letter.

"I have the opportunity to race next year in the American Le Mans Series in the US, a key step towards my eventual dream of success in the Le Mans 24 Hours.

"Unfortunately it cannot be combined with the challenge of full-time government office."

Drayson's position in government is an unpaid post, and the BBC reported that Gordon Brown understood Drayson's decision.

"I understand your desire to take up the extraordinary opportunity which has now emerged to achieve your great life's ambition," the Prime Minister wrote to Drayson.

"I look forward to your return to government when your leave of absence ends."