In the series, the hamlet of Bannermere is in Upper Bannerdale, and on Bannermere, a lake. Black Banner, a 2783-foot mountain is across the lake. Trease wrote about Bannerdale that in 1940 when he went to teach at a private school in Gosforth three miles inland from
Seascale while waiting to be called up: :I had come, all unknowing, to Bannerdale, about which, in the years to come, I was going to write. ... Bannermere will not be found on any map. There is a Banner Dale, scarcely more than a mile long, just east of Saddleback and
Bannerdale Crags looking down on it, but I have never seen them. My own Bannerdale, with its lake and forbidden islet and its sombre mountain Black Banner lowering over it is one of those private fantasy regions that authors, and especially children's authors love to create. It is a pastiche, three parts
Wasdale, one part
Eskdale, with bits and pieces from elsewhere. The 'Gates of Bannerdale' were taken from the Jaws of
Borrowdale, 'Black Banner' was suggested by the real mountain,
Black Sails, and my little town of 'Winthwaite' is
Cockermouth, shifted southwards for literary convenience ... Nowadays ... it does not 'exist merely in my own mind' but exists also in the minds of a lot of people who, in childhood or later, have read the stories I laid there. Not only British children, but – oddly and gratifyingly – Japanese, Swedes, Brazilians and others equally remote. == Social setting ==