Hi Mouldy, prune it in summer after flowering, if it's more than 3 years old, you can cut some branches right down to ground level, and it will send new shoots up, it's a fairly vigorous climber, Derek.

I'm much obliged, Derek!
I only planted it last spring, along with another, which hasn't grown so ferociously. Lol.
I'll just the it in on my trellis, then.
Thanks again, mate. :-)

You're welcome, Derek.