This is just about pruning cordons - there is a much longer piece on growing cordon fruit trees if you would like to know more.
Cordons should be pruned every year around mid August (i.e. about now). Your cordon is ready for pruning when the new side shoots from the main stem(s) become woody at their base. Shorten all of this new growth from the main stem to 3 or 4 leaves above the basal cluster of leaves at the base of the shoot.
Where a shoot from the main stem has a side shoot coming of it, prune this also - to one leaf above the cluster of leaves its base
Pruning of fruit trees is generally carried out in winter or early spring, except for the Prunus family (stone fruit: cherries, plums, damsons, gages, etc), which are pruned in summer. Cordons are different in that you restrict their growth by pruning now and the ideal cordon is compact and covered in fruiting spurs (which this treatment encourages).
You can use this technique on any shape of fruit tree if you wish to restrict its size but at the same time ensure it produces lots of fruit. The trick is to use a M9 semi-dwarfing or MM106 semi-vigorous rootstock
We hope your plants have grown well this summer (certainly not much need to water!)
Watch your plants grow, and enjoy!