Ikea's meatballs can wait. As the sun set on one of the world's longest orbital motorways, the prospect of dinner at the UK's largest branch of the Scandinavian superstore, adjoining Junction 31 at Lakeside, was dwindling. But by then the great M25 road trip had delivered plenty to sate a traveller's appetite.
You might imagine the two questions "How much fun can you have in a day?" and "What's it like going right around the M25?" belong in different orbits in the travel galaxy. Happily, Adam Bates and Julie Calvert, who placed the winning bid for the travel offer in The Independent's charity auction last Christmas, were up for the challenge of a day on the road we love to hate. As generous with their time and flexibility as they were with their donation, they cheerfully agreed to appraise the appeal of the circumference beyond the suburbs.
Any trip involving the M25 is mired in uncertainty, as our first attempt at the trip proved. Adam is the proud owner of a magnificent Bristol saloon. He proposed propelling us around in it. Two hundred yards from home in central London, something solid, necessary and expensive fell off. Instead of a day on the motorway, the Bristol made a trip to the menders. Even when we reconvened two months later, the Bristol staged another mechanical sit-in. I procured a dull old Ford Focus. We set off, only slightly late, for Kent.
Eynsford is one of the prettiest corners of the garden of England. A couple of miles from the turmoil of Junction 3 (where the A20 mutates into the M20 and marches off to Dover), it offers a picture of tranquillity, with a certain misty soft-focus provided by the River Darenth as it meanders beneath a fine Victorian viaduct.
The Romans were impressed, too. Almost two millennia before the bulldozers moved in a mile-and-a-half away, Lullingstone Roman Villa was created. The residence has been excavated, and covered by a pavilion that protects the precious mosaics – and provides space for some superb busts of the high and mighty.
The M25 is the great equaliser, where limousines battle with lorries and everyone has to negotiate the Chevening Totso. What's a Totso? Well, anyone aiming anticlockwise around the M25 from the Lullingstone villa cannot just keep going, because at Junction 5, the Chevening Interchange, the main carriageway becomes the A21. To avoid hurrying to Hastings, you must "turn off to stay on" – in the jargon, it's a "Totso".
Scenically, this is where the best part of the M25 begins. The motorway finds itself squeezed between two other much more ancient arteries: the A25, whose beautiful villages such as Westerham are now able to breathe, and the North Downs Way – a long-distance footpath that is itself based on the ancient Pilgrims' Way between Winchester and Canterbury. Junction 6 provides the gateway to this particular treat, with a twist: neatly braided vines on the south-facing slope of the Downs, courtesy of Godstone Vineyard.
Clamber uphill and within a couple of minutes you reach a wooden sign signalling, with the help of an acorn, the North Downs Way. This pathway, softened by fallen leaves, leads to Arthur's Seat (a gentler viewpoint than the version that looms large over Edinburgh) from which there are panoramic views stretching south to Sussex. The M25 only thinly intrudes on the view. Continue a little further and you reach an excellent pub, the Harrow, serving a good lunch. The staff kindly lent me the phone to speak to Radio 2's Jeremy Vine. Then we headed back to the vines, and the car.
The south-west quadrant of the M25, between the M23 and the M40, is the stretch regularly named and statistically shamed in that fascinating publication Congestion on Inter-Urban Roads. On this particular day, though, the traffic rolled freely enough to get us in minutes to the Royal Horticultural Society's extravagance of efflorescence at Wisley. It was becoming clear that the planners of the M25 had chosen its course purely on the basis of proximity to great tourist attractions. Adam and Julie are, it turned out, horticulture vultures; as members of the RHS, they got in free, but may not have been as thrilled as I was by the graceful geometry of the gardens.
Time for coffee. No service station graces this stretch of the M25, but handily the coffee bar with the best view in the South-east is just a juggernaut's shudder from Junction 14. The location is on the departures level of Heathrow Terminal 5. As you wander over from the car park, you can look west to Windsor Castle. And a window seat provides you with a view over one of the busiest runways in the world. On the apron below, Airbuses beetle about, while every minute or two a Boeing whizzes past the window, carrying hundreds of people with stories from afar – some of which would no doubt be told as the M25 guided them home with their meeters and greeters.
Public art is not a feature of the motorway, and indeed the only significant graffito I spotted adorns the Chiltern Railway arch at Denham: "Give peas a chance". Perhaps this is a veiled reference to the vegetables on offer at the pinnacle of the M25: South Mimms Services.
This is, I promised Adam and Julie, the alpha and omega of the motorway. Junction 23 is where the M25 was born, with the first stretch three miles east to Potters Bar in 1975, and where it was made complete 11 years later with the final link west to Watford. It is here that Britain's prime route, the A1 from London to Edinburgh, meets the M25. That helps to explain why South Mimms is a place known to the world only because of its frequent appearances on radio travel bulletins. Spookily, it is the home to the newest and oldest services on the M25: the original opened in 1987 but was destroyed by fire a decade later.
Today, South Mimms Services is a pleasant enough place, with the feel of an airport terminal with none of that nasty security stuff, and free Wi-Fi. You could use the facility to Google "I hate the M25" and "I love the M25", which score 69,000 and a mighty 400,000 responses respectively. Or you could press on clockwise, with the sun on your rear bumper (a phrase, incidentally, that scores 479,000 on the Google-o-meter).
As the basis for a great circular road trip, the M25 may not match the allure of, say, Highway 1 around the perimeter of Australia. But unlike that 9,000-mile epic, you can revolve comfortably around London in a day. Chris Rea cursed it in his song "The Road to Hell" – but, in the right light, with light traffic and good company, the M25 can seem almost heavenly. Perhaps in centuries to come tourists will wander through the remains of the orbital motorway. For now, make do with the crumbling loveliness of Waltham Abbey: the last abbey to fall victim to Henry VIII's ecclesiastical demolition. We wandered freely through the ruins, and perched on the steps of the 16th-century tower built from the debris of the dissolved monastery.
Far from disillusioned about the M25, we fired up the Focus for the last call – another testament to ideological conflict.
Kelvedon Hatch Nuclear Bunker is beyond the north-east frontier of the M25, but provides a chilling insight into the brutal realities of planning for nuclear war. Three miles from the motorway, you wander through a doorway into a hillside. This is where the results of thinking the unthinkable are carefully laid out, in layer upon layer of nuclear nightmares. The bunker was intended to ensure the survival of, well, a skeleton staff for Britain.
You follow a trail through a sequence of functional chambers: a war room, the Prime Minister's bedroom, and a BBC radio studio ready for Peter Donaldson. The complex was built to withstand a nuclear bombardment even when the average Ikea-bound driver on the M25 had been vaporised. The site was decommissioned in 1992; today, it is the strangest sight within the gravitational field of the orbital motorway.
Travel essentials: Just off the M25
* Lullingstone Roman Villa, Junction 3 (0132 286 3467; english-heritage.org.uk); 10am-4pm daily, £5.90.
* RHS Garden Wisley, Junction 10 (0845 260 9000; rhs.org.uk). Open 10am-6pm daily (weekends from 9am), with earlier closing from November to February at 4.30pm.
* Heathrow Terminal Five, Junction 14; Caffè Nero (020-8759 9424) is at the north end of the Departures level, before security, open from 5.30am until the last flight departs.
* South Mimms Services, Junction 23: welcomebreak.co.uk/motorway-service/south-mimms. Open 24 hours; free parking for two hours; free Wi-Fi.
* Waltham Abbey, Junction 25 (0199 271 4949; walthamabbey-tc.gov.uk).
Waltham Abbey Gatehouse and Bridge (0845 677 0600; english-heritage.org.uk): open 24 hours, free.
* Kelvedon Hatch Nuclear Bunker (01277 364 883; secretnuclearbunker.com). Open 10am-4pm daily (weekends to 5pm), £6.50.