Update: the blade turned out to be a hole, and not a long slit
Well the good news is I fixed the puncture myself, at home with a £7 puncture repair kit.
1. Removed the metal blade ( was a small hole in reality)
2. Use the reamer to clean and expand the hole
3. Thread the liquorice like patch onto the needle like tool
4. Push firmly into the hole, and twist the tool back out leaving the liquorice in place
5. Left it alone for 5 mins
6. Cut off the access with a sharp Stanley blade
7. Inflate to 32psi and check repair with water (no bubbles)
8. Go for a very satisfying blast down some A roads to "test"
Having seen how easy it is to do, I will keep that kit in the car, alongside my compressor and also buy the gunk sealant. The plan is to move across to non runflats when these tyres reach 2mm.
Peter : as always thanks for the information regarding those Pirelli non run flat tyres. I think I will also source those and see if ProTyre can price match. Otherwise I will take a trip to ATS Oxford . Quality workmanship is more important to me.