Three days later I was repeating the process and, seeing nothing obvious to indicate a puncture, dropped into our local Central Tyre depot in Wellingborough. It didn't take them long to discover the problem ΂- right in the centre of the tread was a crosshead screw buried up to its hilt. Drat. A brief discussion as to the possibility of a repair ensued, complete with sucking of teeth and concerned head-shaking. If it could be repaired ΂- a job they'd out-source to a specialist ΂- would I be happy with a patched-up, Z-rated tyre on a ΂£50,000, 1775kg, rear-drive sports saloon? Of course not.

So, three weeks after it was fitted, the hardly worn, ΂£225 P-Zero was rendered scrap by a 2p screw. Just bad luck, but it stings. The only other incident to report was an odd moment when, waiting at traffic lights, I slipped the car into neutral and a warning flashed up: 'Restricted Performance'. And indeed it was, there being no blow from the supercharger.

At the next opportunity I stopped, switched off, restarted and it was business as usual. Strange.