I have a section of wall along my back fence I am thinking of using to
espellier an apple tree. The wall is about 2 m high and 3-4 m long. The soil
is about 12-18 inchs of loam, well draining good stuff.

Question for someone who might know please, do you think I'd be better of
with a dwarf rootstock tree or will a semi-dwarf be ok in that area?

I realise there will be some pruning necessary but I don't want anything
that will get away on me.

I have my eye on a couple of old variety apple trees.

Thanks

Rob