Two really good apples. Pruning as for most, keeping the centre of the tree open (you should be able to throw your hat through the middle of the tree), so that there is a free flow of air through the tree ensuring good ventilation. Summer pruning of newest growth, back by a third or half, and winter pruning of the resultant growth to short spurs. There is very good advice via RHS website and others with videos, too.
Step-overs, cordons, and espaliers require more careful pruning, but the aim is the same, to promote fruiting spurs and keep the tree healthy.

Thanks for that W!. Sounds like usual proceedure for apple trees then. No variation to allow for alleged, partial tip-bearing in 'James Grieve'. Both this and 'Discovery' have lovely flavour, as you say. JB