Should I cut this back now , it only produced 1 flower this year
If you prune it now you are going to remove buds that will produce flowers in 2021.
Do not prune.
Perthshire. SCOTLAND .
Thank you for advise
Also depends on what sort you have, whether mophead or paniculata as they have different pruning requirements.
More info can be found here
Why is it flopping over like that? Is it too shaded or has it been pushed over by another plant? I would prune it down to 1-2ft (possibly in early spring rather than now) and let it come back and establish a better shape, after moving it to a better site. You'll lose one season's flowers but hopefully end up with a better shaped shrub.