There's been one down at Johns Cross roundabout on the A21, East Sussex several days over the last few weeks, on the southbound side.
He doesn't have a van, so I expect there's one parked 1/2 mile further along the A21 and he radios ahead with descriptions to pull.
But what's he likely to be looking for?
Smokey exhausts - that's a obvious candidate. But as you usually don't have to slow down below 20mph at that roundabout, it would be hard for him to see the state of the tyres or much else beyond extreme decrepidness.
Not only, but if he does give you the eye, you have a choice to take the right fork off the A21 roundabout towards Battle and there's not much space down that road for a van + a pull-over spot.
Just curious what they do...