Sawfly. Spray or wash them off at the first sign
Existing bush. Feed, high nitrogen after the leaves have gone to encourage new leaves. Otherwise high in Potash for flowers and then fruit. I used to use Tomorite for this. That needs doing in early Spring or late winter. Otherwise keep the bush well fed and it should fruit again.
As a matter of interest I gave up growing them when I found that there was a whole stretch of them growing wild in the hedgerow where we lived. The leaves on them were stripped every year and they still produced masses of fruit.

Thanks OB, will pass it onto daughter.

when I grew gooseberries they often were defoliated by sawfly but still fruited every year .

finally removed them when I still had the previous years crop in the freezer uneaten. Daughters decided they didn't like them any more. Same with the blackcurrants.

I don't think the lack of fruit is connected with the sawfly. You can prevent the sawfly by spreading black plastic under the bush because that's where the sawfly grubs overwinter and it means they can't get out to infest the bush.(I tried this in desperation and it worked) Its a good idea to spread the February application of potash first, around the time you do the winter pruning, and check that the ground under it doesn't get too dry.(It doesn't usually)
Did your daughter notice whether the bushes actually flowered or not?

(Preventing the overwintering grubs getting access to the bush doesn't stop a fresh lot of sawfly coming in, so keep a lookout for that as well just in case. But you would be unlucky if this happenend)

Thanks very much, let’s see if she gets gooseberries (next) year.

Hank jut a note - the plastic only prevents a re-occurrance of last year's attack - it won't prevent a new infestation from mature sawfly flying in.
Just found out there is a nemotode treatment too if you like that sort f thing.

Thanks Y, will pass that onto daughter.

YL, daughter never saw any flowers.

How disappointing Hank. Never come across that before and can only suggest adding some potash in February when she does the late winter pruning. Unless of course she pruned it too hard last winter and cut the flower buds off - quite possible :(

Thanks again YL, will pass that on . H.