Michael Corby wrote:
I realise now's the time to do it, but I'm anxious to do it properly so that
I don't ruin the shape. My husband is keen on a Texas Chainsaw Massacre,
but I don't feel that is wise.

It's a mature plant - we've lived here for 8 years and it was mature when we
bought the house. It's huge and occupies most of our pocket handkerchief
backgarden! We've got the prunings collection on Monday, so I'd be glad of
your advice today!

Why do you want to prune it?