approach Shepton Mallet, our road is rudely dislocated. It's as if some great geological fault has sheared, breaking the continuity and moving the ends a mile or so apart.
Of course, it's nothing so dramatic. This is just a reminder that the A361 is not a trunk road, striding purposefully across the nation to its destination. It's just a number - assigned to a chain of pre-existing roads which happen to go in the same vague direction.
Here, the road from Frome meets the A37 just before Shepton. A mile South, the road onwards towards Pilton also makes a junction with the A37. The Ministry of Transport decided they should both be called the A361.
This "fault line" (the A37) is, in fact, the modern descendent of Fosse Way - the Roman road from Bath to Ilchester, its straightness preserved in 20th century tarmac.
The Romans didn't just march through here, they built a reasonably large settlement at this point, straddling the road. At first sight, it might seem a strange place to set down roots - there seems to be nothing particularly special about the site, deserving of an Imperialist's attention. There is something undefinable about this area which, even today, engenders surprise that a town should grow here. Most towns feel as if they belong where they are - that if they didn't exist, someone would have to invent them. Shepton isn't like that - if it wasn't here, no-one (except a Sheptonian) would be very surprised.
Yet the evidence suggests that there has been settlement here or hereabouts for a very long time - long before the Romans arrived, looking for plumbers' supplies.
One upon a time, the Mendip Hills around here were riddled with mines, giving up lead, tin, silver - even some iron. At its peak, Britain was the most important metal resource in the whole Roman Empire. Those metals came either from here in the Mendips, or from Cornwall.
The Romans didn't discover these resources; they were known about and exploited long before they came. Those great Eastern Mediterranean travellers, known as the Phoenicians, had travelled all the way here to trade for ingots, hundreds of years before.
It is arguable that these ores were the only thing that made Britain worth invading. The Romans certainly didn't come here for the climate.
Of course, Julius Caesar never got this far on his short visits, but when Claudius' armies conquered Britannia nearly a hundred years later, the legions were encamped around Shepton within a year of their arrival on the island. Very soon, massive shipments began to make their way to Rome - much of the plumbing in ancient Rome came originally from the Mendips (Latin plumbus=lead).
The lead and tin were also mixed to form pewter - and Roman Britain had a widespread reputation for fine pewter-work.
Not much is known about the methods of extraction of these metals, but we can be pretty sure the ores came from many small mines, rather than a few big ones. The smelting too would have been handled by small scale crucibles - probably fuelled by charcoal.
The Mendips aren't a range of smooth, regular hills - they're a jumble of broken hillocks concealing hundreds of isolated valleys. Even today, you can come across concealed, dead-end valleys, with farmhouses and farmhands who seem to belong to some other time - or some other planet. (Carry the banjo music from "Deliverance" in your head, and you'll get the idea.)
Back then, with dust-caked trolls emerging from the underworld, with strange sounds of hammering and grinding, with fierce fires burning in secret nooks - it must have been terrifying. I expect the fearless Roman legions huddled together in Shepton and let the metal come to them.