Johnny
As mentioned - plums are pruned when in leaf due to the risk of a
fungal disease called silver leaf. Infection leads to felling. If a
branch has to be removed in the winter due to storm damage - cut it
and seal with Stockholm tar, available from equine suppliers who use
it to stop foot rot on horses hoves. You might get it from an
agricultural merchant that sells stuff for livestock.
Once a plum has gone to full height you have one of two options -
leave it or take a risk and cut it back to a reasonable height and
start retraining it as you would like it. If you do this there is a
risk of infection with silverleaf but if the tree is
unmanageable.........

As far as apple go:-
For your apple tree the winter pruning approach would be as follows:
As the tree has not been looked after for a while then pests and
diseases can be an issue, particully once you start stiring things up
by pruning. Here are a few
steps to take.
..
First, this kind of pruning is done when the tree is dormant and
there
is no hard cold spell that could damage the exposed tissues. (so you
have go a couple of weeks to get teh job done) Secondly
if there is a lot do do, then the work should be spread over at least
two, preferably more, winters. As the tree is of an age, be careful
as
to what is safe to stand on if you are climbing it.
..
1. As with any pruning remove any dead, dieing or damaged branches.
Think larger banches rather than the fine growth, those that need a
saw
rather than seceteurs. For the most part you will be cutting back to
healthy growth.
2. Remove branches that are growing the wrong way - they want to bee
going outwards not back into the crown of the tree.
3. Next are the crossing branches, here you need to stand back and
look at the tree from several positions to descide which branch to
remove.
4. Deal with branches that are too high, too low and too spreading.
Having done all this you will start to have a framework to work with.
5. Then it is a question of overcrowding. This is the enemy -
congestion limits light and air flow.
6. To help prevent fungal infections spreading, paint over large
wounds with a fungicidal paint such as Medo, available from good
garden
centres.


The best advice I can give is to take your time, follow the steps in
order. Yes you are likely to go around the tree a few / several
times,
but by following the steps you avoid being too drastic and being left
with a stump.


Winter pruning encourages growth, so don't be suprised to see lots of
new growth next season. Come summer, the new growth can be thinned
to
select new branches.


It will probably take three to five years to get the tree


The RHS has a leaflet - which can be found at
http://www.rhs.org.uk/advice/profile...fruit_tree.asp

Good luck
Clifford
Bawtry, Doncaster, South Yorkshire