Woods from years ago, and how NOT to prune a tree

A couple of weeks ago I visited my parents, near Manchester. Here's some pictures of woods I used to play in as a child, and also some appalling pruning of a tree that I saw.

Here's the path at the back of my parents' house, it used to be a mining railway, but is now a haven for wildlife, probably because as a strip of trees a few metres wide it is almost entirely "edge":Carrying on from there we headed past a gully that I remembered having much smaller trees in it!The really weird bit was coming to piece of ground that's split into two levels with a slope between them. We used to set up a ramp and jump our bikes from the higher to the lower level, but you'd struggle to ride through it now:
Interesting to see what can happen to some bare land if left alone for 20 years.

One really cool thing we saw was a Great Tit making its home in this hole that a woodpecker must have made in a dead tree:
Anyway, onto the poor attempt at tree surgery that we saw. This was on a bit of land just at the edge of someone's garden, so not actually part of the wood. They'd pruned off some lower branches using a chainsaw (probably up a ladder with a chainsaw meant for use on the ground...). Here's the results of their work.

First, the stump of a branch that they seem to have just hacked off, with no attempt to tidy it up:
Then one that's a bit tidier, but where they overcut and went into the main trunk:
And finally, one where they didn't make an undercut so the branch has peeled back bark from the trunk as it came down:
None of this is going to help the health of the tree, opening it up to infection, etc. It'll be interesting to see how it's doing when I'm next up there...

Mike