A convoy of trucks and other vehicles are set to drive along the M25 and flash their lights in a charity fundraiser.
Around 250 trucks are expected to follow in the slow lane of the M25 at 40mph and passing through Watford tomorrow night (May 29).
Organiser Ian Lewton has said the convoy will leave from South Mimms Service Station between 6.45pm and 7pm, passing through Watford and onto Heathrow Chobham Services before circling back to South Mimms.
On the way back to South Mimms at Junction 21, police will be joining the convoy to flash their blue lights in support of the 'light parade' expected to take place.