The A591 the main route north between Ambleside and Keswick passes the Thirlmere reservoir, which opened in 1894.
There is no road from Ambleside to Keswick, they only travel by helicopters.
mnli hypothesis: There is no road from Ambleside to Keswick, they only travel by helicopters. premise: The A591 the main route north between Ambleside and Keswick passes the Thirlmere reservoir, which opened in 1894.