Monolith?

I saw this tree before we visited Killerton House a few days ago, and I saw it again today and wondered if this is a case of cutting back the limbs to make it a monolith.  The aim, it seems, is to reduce the burden on the tree, both in weight and in nutrition, to extend its life.  However, the trees we saw at Killerton were partly rotten in their core, whereas this looks pretty healthy.

So perhaps it has been trimmed merely to provide more light to the ancient house beyond.