Firstly, welcome to the Forum !
Secondly, yes you are correct, it is a Tree Bumblebee - Bombus hypnorum.
This one has the classic colour pattern. They are often darker in thorax colour, down here in Bucks where I live.
It has already been seen in Scotland, so Cumbria should have been settled last year or before !
To see details of the first finding in Scotland, take a look at the BBCT “News” pages.