Dr Desmond Babbage having set the path for sound horticultural
prozelytising of the masses via garden banter, here go my own bit of
hard earned expertise.

To prune your apple trees, wait till 23rd April - unless it is very
wet, in which case leave it to 29th - and carefully cut with a very
sharp secateur just above the second-last outward facing bud on all
branches whose diameter is less than 0.9cm. This will promote vigorous
growth and fruit setting.
Around 10th May, you need to bare the top 15cm of each branch,
methodically removing all leaves, flower buds and other signs of
vegetation, such as they may be.
On 25th June, you need to prune the branches again, removing about 1/3
of every branch whose diameter is less than 1.3cm - cut just above the
third inward facing bud on the right.
Around 16th July - or a couple of days earlier if the weather is very
warm - you may start regularly chopping a few centimetres off each
branch regardless of diameter. Just nibble away, using sharp secateurs
for the thinner branches, anvil loppers for the slightly larger ones.
By 25th August, you need to tidy up the tree to prepare it for winter,
by neatening all branches close to the trunk - this will stimulate
greater vigour for next Spring.
From October, you can bring the trunk down to about 30 cm from the
ground.
You may not get a whole lot of apples, but you'll get plenty of timber
to keep you warm.

Cat(h) (Disinguished Fellow of the RHS, Fruiting Tree Division)
(It must be Friday)