On 01/02/2018 21:05, Vir Campestris wrote:

All our books say "Don't need pruning" - which may be true normally. But
this one has been mostly shaded for years. We've cleared out the boring
shade plants, but it's very "leggy" - not much at all near the centre
(and one thick branch has plastic rope embedded in it )

Is there anything we can do, and if so when?

Around now should be OK. I'd go for pruning out 2/3 of the worst wood
and any crossing branches leaving the newer short and stocky branches
alone (a bit like for dogwoods). You will obviously lose a lot of
flowering wood for this year but you should be able to prune it.

If nervous take out the worst third of old leggy wood and do it over a
few years after seeing how it reacts to a bit of hard pruning.

--
Regards,
Martin Brown