Dash I reckon its the Southend coppers mate. I remember a few months ago I was zooming in along that lovely bit of straight road from Hockley/Rochford down to the Tescos roundabout. Basically just doing some test runs in the middle of the night, setting up my ignition timing, nitrous flow rates etc. Anyway, every time I did a run, I would stop and try different settings which had to be done under the bonnet. So two coppers in a panda car drove past me, stopped turned around and came back and pulled up alongside. They asked if I was having any trouble (luckily I had just shut the boot so no nitrous bottle on display). So I couldnt exactly say I was doing test runs up and down the Queens highway so I pretended I was getting a misfire or something, and I didnt need any help Id have it fixed soon. The copper asked whether it was a Williams, and had I done anything to the engine. So I lied and said just a few cosmetic improvements, nothing major...
Anyway later on down at Tescos I bumped into them again as I was filling up with petrol! They pulled up and had a chat about cars and they obviously knew this was no standard Clio; in the end we go talking about 1/4 miling!