With the advent of war, the 1940s saw little in the way of site development other than safety measures for potential aerial bombardment.

In 1940, air raid shelters were inserted in the gaps along the front of the school , restricting the entrance for pupils to ‘tunnels’. The Girls' School ‘tunnel’ is still there, functioning as a pupil entrance. Large windows were later added to the adjacent shelter to turn it into a cloakroom and, later still, a classroom. The year also saw the Schools evacuated again, this time near to Windermere, where they shared buildings with Windermere Grammar School and Kelsick Grammar School, Ambleside.

After the war, growth in pupil numbers meant that there was a need for more space, but shortages of building supplies meant that only the Small Dining Hall could be built behind the kitchens. This building was converted into classrooms in the 1980s and will be removed as part of the new development.