Some more.
Left: WS19 MK.I, II & III North America ZA. 21575 (British??), 42 pages.
Right: WS19 MK.I, II & III Working Instructions, ZA. 21575, December 1949, War Office Whitehall, 40 pages.
Left: WS19 Mk.II Working Instructions, PC 90772C-195 July 1, 1942, Ottawa Canada, 93 pages+-.
Right: Same as above, but August 1, 1942, 116 pages+- (has photos and fold outs that the July one is missing)
Left: WS19 Mk.III Working Instructions, RCA 113923-1, Ottawa Canada, 135 pages+-.
Right: Same as above, 135 pages+-, smaller format.
Geoff