discussion of whether it's better to take the A30 to Stockbridge and then the A303 to Ilchester or the A361 to Glastonbury via Shepton Mallet. Within minutes the conversation will plunge off into a level of detail that leaves you, as a foreigner, swivelling your head in quiet wonderment.
'You know that layby outside Warminster, the one with the grit box with the broken handle?' one of them will say. 'You know, just past the turnoff for Little Puking but before the B6029 mini-roundabout. By the dead sycamore.'
At this point, you find you are the only person in the group not nodding vigorously.
'Well, about a quarter of a mile past there, not the first left turning, but the second one, there's a lane between two hedgerows -they're mostly hawthorn but with a little hazel mixed in. Well, if you follow that road past the reservoir and under the railway bridge, and take a sharp right at the Buggered Ploughman -'
'Nice little pub,' somebody will interject - usually, for some reason, a guy in a bulky cardigan. 'They do a decent pint of Old Toejam.' '- and follow the dirt track through the army firing range and round the back of the cement works, it drops down onto the B3689 Ram's Dropping bypass. It saves a good three or four minutes and cuts out the rail crossing at Great Shagging.'
'Unless, of course, you're coming from Crewkerne,' someone else will add eagerly. 'Now, if you're coming from Crewkerne. ..'
Give two or more men in a pub the names of any two places in Britain and they can happily fill hours. Wherever it is you want to go, the consensus is generally that it's just about possible as long as you scrupulously avoid Okehampton, the Hanger Lane gyratory system, central Oxford and the Severn Bridge westbound between the hours of 3 p.m. on Fridays and 10 a.m. on Mondays, except bank holidays when you shouldn't go anywhere at all. 'Me, I don't even walk to the corner shop on bank holidays,' some little guy on the margins will chirp up proudly, as if by staying at home in Staines he has for years cannily avoided a notorious bottleneck at Scotch Corner.
Eventually, when the intricacies of B-roads, contraflow blackspots and good places to get a bacon sandwich have been discussed so thoroughly that your ears have begun to seep blood, one member of the party will turn to you and idly ask over a sip of beer when you were thinking of setting off. When this happens, you must never answer truthfully and say, in that kind of dopey way of yours, 'Oh, I don't know, about ten, I suppose,' because they'll all be off again.
'Ten o'clock?' one of them will say and try to back his head off his shoulders. 'As in ten o'clock a.m.?' He'll make a face like someone who's taken a cricket ball in the scrotum but doesn't want to appear wimpy because his girlfriend is watching. 'Well, it's entirely up to you, of course, but personally if / was planning to be in Cornwall by three o'clock tomorrow, I'd have left yesterday.'
'Yesterday?' someone else will say, chortling softly at this misplaced optimism. 'I think you're forgetting, Colin, that it's half-term in North Wiltshire and West Somerset this week. It'll be murder between Swindon and Warminster. No, you want to have left a week last Tuesday.'
'And there's the Great West Steam Rally at Little Dribbling thisweekend,' somebody from across the room will add, strolling over to join you because it's always pleasant to bring bad motoring news. 'There'll be 375,000 cars all converging on the Little Chef roundabout at Upton Dupton. We once spent eleven days in a tailback there, and that was just to get out of the car park. No, you want to have left when you were still in your mother's womb, or preferably while you were spermatozoa, and even then you won't find a parking space beyond Bodmin.'
Once, when I was younger, I took all these alarming warnings to heart. I went home, reset the alarm clock, roused the family at four, to protests and general consternation, and had everyone bundled into the car and on the road by five. As a result, we were in Newquay in time for breakfast and had to wait around for seven hours before the holiday park would let us have one of their wretched chalets. And the worst of it was that I'd only agreed to go there because I