The message
from Lynda Thornton contains these words:

I personally wouldn't recommend picking when still greenish and firm,
even if they're sizeable berries - I picked some from my bushes a bit
early this year and ended up with a bit of a stomach ache, even though
they'd been cooked for ages before being cooked again in a crumble!

Probably cooked beyond digestion :-) We had fresh gooseberry fool on
Sunday, made with firm green rinsed gooseberries cooked with a little
sugar for about 10 mins till they were soft enough to rub through a
seive; stir in thick custard and cream, and chill.

Janet.