Automotive tycoons Reginald and Billy Rootes (Hillman, Humber, Commer, etc.) were first to respond to Government's call for Shadow Factories, each intended to be shadow (duplicate) of parent, 1936. Shadow factories often larger than parent, with far better facilities for mass-production. Rootes plants included Speke (Liverpool) making Bristol Blenheims, Blythe Bridge (Staffs.) making Blenheims and Beaufighters, and 3 giant factories making poppet- and sleeve-valve engines.