Hi it looks like Blister mite. Not a lot you can do but check the RHS link below.
https://www.rhs.org.uk/advice/profile?PID=%20789

Thank you Seaburn. I think that is what it is. I only bought the vine last year, and it was fine all through the summer. I wonder where this mite came from? I only have the one vine, and no one else around here has a vine that I know of.

Is it growing inside or out?

Mine are outside but I've not seen anything like that, hence my asking just in case I should keep an eye open

From what I have read they could well have been eggs on the vine when you bought it.
at least it wont affect the fruit.

It’s outside

One more question, please…..
Will the vine be forever affected by blister mite now?

possibly unless you can pick off the affected leaves before they lay eggs.

Thanks Seaburn. I’m loathe to take too many leaves off…..

I get it on my red currant and last year I wasn't well and didn't remove affected leaves as they appeared as I usually do. This year the first affected leaf has just appeared, much earlier than usual. If you don't tackle it straight away it will just get worse . Don't compost the leaves and don't miss any.