Heavens, I'm not as good at this as you think I am
What a beautiful orchard and setting though, with the sheep and poultry and sunshine
I have read what I wrote to chairmanphil and I think the same applies to your trees, once the leaves are off in the winter. In the meantime though there is something you can do, which is to cut back all that tall growth, which is best seen in the fourth and fifth pics. I would be tempted to take it all back by half now - what do you think Dan and your book? Because it's not just a single years vegetative growth it's not totally straightforward. However, once the leaves are off you could post more pics of each tree to see how best to deal with them to give you fruit and not loads of branches. Bramleys tend to crop heaviest in alternate years so lets see if we can get next year to be a bumper crop.
I can't help much about the canker, except that in the winter the branch stumps which have been cut off about a foot out from the trunk need to be cut closer in. They are the sort of place where canker can get a foothold. Unfortunately the rot may have gone beyond those stumps, but we'll see in the winter.
Another point about infections in trees is to be very careful about hygiene. I take a tin of white spirit or meths and an old toothbrush with me when I prune, and after I have cut any suspect wood I scrub the saw, pruners or whatever I have used. Sometimes this means doing it after every cut. I didn't do this when the trees were first planted (because they appeared healthy) and it's probably why canker spread through my little orchard, but it seems to be helping now. Sawdust from pruning is probably responsible for spreading the infectious material too.
I think I went to the wrong school - I wish I had been taught pruning at that age. Even my Dad didn't show me then - I had to wait until I was middle-aged and he was fed up with doing my pruning for me