The message
from "Alison" o.uk
contains these words:

How hard back can you prune an escallonia, assuming you want it to survive?
Into old wood?

I've got one (5ft x 6ft) which got battered last winter when a large
tree beside it was taken down. I cut the broken branches right back to
the trunk and ended up with the bush halved vertically. All the old wood
sent out loads of healthy shoots which look so good, I'm thinking of
taking out the other half next year.

Janet.