Thanks for all your reply's.
You had a lucky escape Ken on the M6. Reassuring to hear Goop has no effect on the bike's handling, Good vid, Delboy's Garage is well regarded on youtube but I hadn't seen that one so cheers for that.
Just before I had my new tyres fitted the MOT guy pointed out I had a small piece of Steele in the back tyre but not losing any air. when I got home I pulled it out and was amazed it was a small staple, like out of a book or magazine, how on earth could a small soft staple puncture a Michelin tyre, I put a Plug and Go bung in but was losing about 4psi every couple of weeks and both back and front tyres were coming up to replacement so that was that.