The trip, which spends four hours touring the ‘sights’ of the 117-mile motorway,  takes in the “amazing sights” of the Queen Elizabeth II bridge in Dartford, Kent, and Heathrow Airport’s Terminal 5.

Brighton and Hove Bus Company launched the tour in its 2012 tour brochure.

Spokesman Roger French told the BBC that the motorway – known for being one, long, frustrating traffic jam – was “absolutely fascinating”.

He added : “It goes through six home counties and you get a whole taste of the variety of London.

“In Essex you come to Epping Forest and coming round by Heathrow you see the planes coming in to land.”

The motorway has been referred to in the past as “the UK’s biggest car park”.

But, defending the decision to add new tour dates, coach firm spokesman Simon Ashcroft told the Daily Star: “I think the M25 is worth looking at in a bit more depth, especially now there are new services being built at Cobham in Surrey.”

The new dates have been added in April and May.

Picture: Getty