Gooseberry sawfly. Bit late to do anything about it now. Next year you need to spray at the first sign of damage (and that is not always easy. They seem to eat it overnight). As for this year, give your bush a good watering and feed with a high nitrogen feed to help it grow new leaves. Don't worry, the sawfly damage does not kill the plants.

Thanks Owdboggy will do that. It happened when I turned my back was looking out for it or whatever it was from experience of last year. What do I spray it with?

Have to confess to using an insecticide on this one. Find one which is allowed to be used on Fruit as some of them are not.
It gets me too, sometimes. One minute there are leaves, the next.......whoosh. Speedy little beggars.

Mine was taken out the other day by little green caterpillars - look closely at the edges of the leaves (or what is left of them).

So.............went out armed with a lump of kitchen paper and a pair of tweazers, tried wiping them off but they clung fast, I took great pleasure in squashing the blighters. They were hard to see especially as I'm very short sighted, had to get down on my knees to look closely.
Will take another look later, gave them a good feed as you said Owdboggy we'll see how it goes. Thank you both for your help.