what did you do with your fazer today ?

[Grahamm]

That's what I thought, trouble is when you look at the tyre really close up it looks like a split not a cut, as if the tyre has got a manufacturing fault.
Its a Contimotion and found on the web there was a recall a couple of years ago for Contiattacks but only a certain size, not my size tyre. When I get it replaced on Saturday morning I am going to keep the old tyre and send some photos to Continental, see what they say.

Check how old the tyre is (see https://www.kwik-fit.com/tyres/information/tyre-age ) and when you had it fitted. It might have been old when it was "new" on the bike.  If so, you should have words with the fitter...