Q From Paul Hughes: Where does the term barking mad come from? My theory is that it comes from: One stop short of Barking, referring to the London underground station. Any other ideas?
A I can see the way you’re thinking: there are lots of phrases along these lines (sorry, accidental pun) that suggest somebody has less than his full complement of little grey cells: “Two sandwiches short of a picnic”, “three sheep short in the top paddock”, “two bricks short of a load”.
And the name of the East London suburb is a seductive choice for the origins of this slang term. Peter Ackroyd, in his recent book London: A Biography goes so far as to suggest that monks in medieval times had a lunatic asylum there, which gave rise to the term. The problem with Mr Ackroyd’s idea is that the evidence strongly suggests the term is nothing like so old as that.
The Second Edition of the Oxford English Dictionary contains not a single reference to barking mad and I can’t find an example in my electronic database of more than 4,000 works of literature. Eric Partridge, in his Dictionary of Slang and Unconventional English, dates it to about 1965.
Nicholas Shearing of the OED kindly hunted through their database of citations and found that their earliest reference is actually from as far back as 1933, from Mr Jiggins of Jigginstown by Christine Pakenham (Countess Longford): “But he was mad! Barking mad!”. By the 1960s, barking was being used alone. Subscriber Anne Hegerty found this in a Nancy Mitford story, Don’t Tell Alfred, of 1960: “If Dr Jore comes here every day like he says he’s going to he will drive me mad. Really, properly barking”.
All these pointers add up to a strong presumption that barking mad is a bit of relatively modern British slang. The idea behind the saying is most likely that the person referred to is so deranged that he or she barks like a dog, or resembles a mad dog, or one that howls at the full moon.