Photo would help. Probably gooseberry sawfly

Hi Beegee, I gooseberry sawfly. they lay eggs and they develop into caterpillars that then munch away from the underside of the leaves. If there are still any caterpillars left pick them off and destroy them.

Sorry Seaburngirl = we must have posted answers at the same time!

Shouldn't affect next year's new growth but keep watch as when you've had them once they'll probably be back.

Thanks for all replies I'll have to watch them next year