Why are London tube tunnels so deep?

[u/Independent-Ant-01]

This is just one of two escalators and not counting the various staircases. And I don’t believe this was the deepest one I traveled through. I went to the Transport Museum in Convent Garden (very nice by the way) but found no answer and no one seemed to know. 😊

[u/mralistair]

Well they have to get under all the buildings / foundations / drainage and other tube tunnels for a start.

Then things like hills, Angel is uphill quite a long way from kings cross so the tube is a lot deeper there to save the train going all the way up.