I've decided I'll take the risk and prune this as I did last autumn,
with the same caution I'd exercise over a lavender and maybe straight
after flowering.

I'll probably try and be a little more strategic because at the
moment, the plant's long robust bare legs (growing almost
horizontally) are starting to become covered with a canopy of new
growth growing backwards towards the origin of the plant (if you see
what I mean). I'll leave that reverse growth to flourish (hopefully)
while trying to keep its relentless onward and upward march in check.


Thanks for everyone's thoughts on this.