Most drivers usually want to get off the M25 as quickly as possible.

But for one pair a charity challenge is set to see them sit on the motorway - dubbed the world's biggest car park for 24 hours.

The drivers include professional racing drivers Alexander Sims and Jody Fannin who will share the wheel of a BMW i8 hybrid supercar.

It got underway at 4pm today at Clacket Lane services and the drivers will attempt a day's continuous driving around the London orbital road, finishing at 4pm tomorrow.

The mission is to get as close as possible to the theoretical maximum distance that can be covered in that period - 1680 miles. Breaking the speed limit will not be an option, but roadworks, jams and temporary speed limits are all hazards likely to crop up.

The event takes place exactly two weeks before the world famous Le Mans 24 Hour race and follows the same format of three drivers taking it turns to be at the wheel, with driver swap pit stops at Clacket Lane.

Jody Fannin is 23 and drives for Ferrari team JMW Motorsport in the 2017 European Le Mans Series. He is one of the sport’s rising stars and one of the youngest British Racing Driver’s Club (BRDC) members.

He was born prematurely at 29 weeks and he is using the attempt to generate money for children's charity Buttle UK. It improves the lives of youngsters living in poverty and crisis.

Alexander is keen to highlight the environmental issues faced by motor transport today as well as solutions already available from the automotive world.