I found this in a 1942 Pick of Punch annual. It's not about colour, but is fun nevertheless. For anyone who doesn't know the history of WWII clothing restrictions, this article † from the National Archives explains it, including the rôle of Norman Hartnell and Hardy Amies, their styles, and how ration coupons worked. There's another explanation here ‡ from the Imperial War Museum.
† "Fashion or ration: Hartnell, Amies and dressing for the Blitz" by Robert Daoust, The National Archives
18 February 2010
‡ "How Clothes Rationing Affected Fashion in the Second World War" by Laura Clouting and Amanda Mason, Imperial War Museum
5 January 2018
A men's outfitters. A customer is walking away from the counter and out of the shop, wearing a suit. The jacket and trousers are made from rectangles of differently-textured and patterned materials stitched together. The tailor is saying to his assistant, "And there goes the last of the pattern-books."