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
https://media.nationalarchives.gov.uk/index.php/fashion-or-ration-hartnell-amies-and-dressing-for-the-blitz/
18 February 2010
‡ "How Clothes Rationing Affected Fashion in the Second
World War" by Laura Clouting and Amanda Mason, Imperial War Museum
https://www.iwm.org.uk/history/how-clothes-rationing-affected-fashion-in-the-second-world-war
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."