Apple tree

We have several apple trees in the garden but this, down in the wild garden, is far and away the oldest. It is huge, almost completely hollow, and the bark spirals around the trunk in a way I love. The apples are small and extremely sour, so I think they must be cider apples (we also have a Worcester black pear tree which produces perry pears). The canopy is very big, and occasionally a branch breaks in a gale, at which point we have to have it properly ministered to by a tree surgeon. One day I suspect that the whole thing will topple - but not, I hope, till after we have moved away, because losing it would make me very sad.