Pruning may be carried out during early spring if a greenhouse is available, otherwise it is best not to attempt it until all signs of frost have disappeared.

Sorry about the green house bit lol - Cant see your hedge being in a green house -- But a rule of thumb is after all signs of frost of gone

Usually April in the south, possibly later where you are - a couple of weeks after growth has got going, basically. If its a very old, large hedge and now looks very untidy, you can just lightly trim the longer growths back if they're a problem, but only the barest minimum.

Thankyou so much, it would have been a problem to bring the hedge into the greenhouse, but I shall just take the very long untidy stems off. Another
Fuscia worth looking at is Fuscia arborenses easy to
take cutting and has flowers like a lilac bush hardy in most ares, but I do keep mine in a big pot in case of very low temperatures

Hmm, let me just check, my answer assumed your 'hedge' was in the ground - is it? If its in pots, then its vulnerable to being killed by winter temperatures through its roots even if its a hardy fuchsia variety.