‘Codswallop’ means ‘Nonsense, rubbish, drivel’. The experts at the Oxford think they have nailed it down. They write, ‘Popularised in this sense, which they may have coined, by writers Alan Simpson (1929-2017) and Ray Galton (1930-2018), who used it as a euphemism for a stronger expression (e.g. cobblers, bollocks – both banned at the time by the BBC)) in the comedy series Hancock’s Half Hour and Citizen James in the late-1950s and early-1960s, chiefly in dialogue delivered by actor Sid James.’ The word did exist before they popularised it. In an interview Alan Simpson said, ‘In the thirties, I was about seven or eight and my uncle used to use it as a proper noun, he used to call me codswallop.’ It’s recorded as a mild put-down from around 1928, but it appears to have been given its current meaning by the highly inventive Simpson and Galton.