Nick Maclaren writes

Summer jasmine can be pruned (or hacked) now, but winter jasmine
should be left to flower (if it does after this frost).

You keep making comments like this! I guess 400ft up in Yorkshire is
warmer than Cambs, but even so, my jasmine has been flowering steadily
on a N wall since early November, frost or no frost. I can't get over
the difficulty you have with yours.

--
Kay