and I'm not sure how far down to take it. It's a standard (or thinks it is) so the
rootstock is pretty vigorous.

I'd appreciate it if anyone with any experience of remedial pruning would take
the time to post an edited version of this, maybe with marks where you would
cut. At the moment the tree has some canker in the upper branches, and as with
many old trees only fruits right at the top. I'm quite prepared to go without
apples for a couple of years if it means we can keep the tree!