grafting...

a branch onto the aforementioned shaggy larch. There's a big empty space at the back of the tree and there's nothing nearby that is suitable for wiring there. One of my books describes drilling a hole through the tree taking a branch from another (does it matter if it's japanese or european?) stripping the bark and poking it through the hole and sealing the hole up with cut paste. All sounds a bit bloody barbaric to me. If I decide to go ahead, should I do this now, in the winter or leave it til next spring which seems the most sensible option?

The branch that you graft in must be identical or you end up with a tree that has different characteristics, such as needle colour or twig colour on different branches. It's easiest to grow a long branch on the tree on purpose, so you can bend it around to where it is needed and graft it in. That way it is genetically identical. Larch tend to be quite cooperative in respect of growing long straight whippy shoots if left untrimmed,