I spoke to our resident tree expert at works (He did / does TPO's)
The tree is a sycamore tree
In it's location it is away from other trees and so is not competing for light or nutrients.
It's main threat would come from deer nibbling at it, and possibe water run off, however there already is a tributary further down stream, image attached, making this unlikely. Although it looks fragile it seems in an ideal location.
Incidentaly I was staying at the
Calvert Trust