Day trippers touring M25 by coach
A coach-load of day trippers is taking a 117-mile (188km) tour of the motorway dubbed by frequent users as "the UK's biggest car park".
The £15 tour of the M25 started at junction six at Godstone in Surrey and was expected to take four hours barring major hold-ups.
An early landmark on the clockwise tour was Heathrow Terminal Five, where the coach stopped for a closer look.
Brighton and Hove Bus and Coach Company plans three more trips this year.
One of the passengers, Bert Bonnen, said: "I've heard there were a few hold-ups on the M25 this morning, but we hope to be home by tomorrow."'Little bit mad'
The tour started with two pick-ups in Worthing and Brighton on the south coast and reached the M25 about 11:30 GMT.
The 38 day trippers on board are listening to a commentary from one of the company's drivers, Nigel Pullan, who has researched the history and landmarks on the road around London which opened in October 1986.
Other sights on the motorway, which passes through six counties, include the Queen Elizabeth II Bridge at Dartford and Epping Forest.
Retired lorry driver Mr Bonnen, from Telscombe Cliffs in East Sussex, said: "I was driving round the M25 many years ago and driving has been a big part of my life.
"When I saw the advert I thought I wouldn't mind doing it.
"When I mentioned it to my dear wife she didn't want to know and thought I was a little bit mad but I managed to talk her round."
Mr Pullan's non-stop commentary includes pointing out all the junctions and intersections along the route.