Thirlmere sits on the juntion of two low flying routes in and out of Windermere/Keswick. One goes off between Garburn and Kirkstone Passes then there’s a fork to either drop down to Ullswater or cross between Fairfield and Helvellyn and into Thirlmere.
Once into Thirlmere there’s another fork, either right down the valley into St Johns in the Vale or left and over the northern end of Derwent and up to Bassenthwaite.
I’m surprised they didn’t object in the first place. They normally do.