Why destroying London would not erase Britain's war effort

What would happen if a meteor destroyed London in December 1939?

Britain would suffer a severe political and human disaster, but dispersed military institutions and leadership outside London could preserve its war effort.

Britain's commitment to the war and its institutions outside London are central to this counterfactual. Important military activity and research had already been distributed beyond the capital, reducing the chance that one disaster would remove every command and technical center. George VI would probably have been at Sandringham for Christmas, avoiding an immediate royal succession crisis. The services would lose people and headquarters capacity, but their personnel and organizations elsewhere in Britain could continue operating.