Right then. For anyone who's interested here's the outcome.
So into my garage I went, armed with ignition key and a pair of pliers. I started her up, pulled out the nail and snicked her into 1st gear.
Ultraseal pissed all over the floor and the tyre went down.
Steve
That's a bit worrying - what size was the hole ?
Glad to hear you got a proper repair done - one less 'niggle' at the back of your mind
Bob.
For god sakes It even prevents you from fixing a puncture in the time honoured fashion if you do get one. It's pointless (pun intended).