Scabby grapes

This is the first year my Italian vine has produced grapes. I don't know the variety or colour but it was sent to me by a friend in Northern Italy 2 years ago. It's growing outdoors in SE England against a South facing wall. It's in a well enriched clay base soil and I'm feeding it twice weekly with a general purpose liquid fertilizer. The fruit set wasn't great but the vine looks very healthy and vigorous. I've just noticed that some of the fruit have what looks like small brown scabs on the skin.At the moment only a couple of bunches are affected. Any ideas please.