I've been hearing this phrase around, and just had to look it up.
Originally posted on www.worldwidewords.org
[Q] What is the origin and actual meaning of bob’s your uncle?
[A] This is a catchphrase which seemed to arise out of nowhere and yet has had a long period of fashion and is still going strong. It’s known mainly in Britain and Commonwealth countries, and is really a kind of interjection. It’s used to show how simple it is to do something: “You put the plug in here, press that switch, and Bob’s your uncle!”.
The most attractive theory—albeit suspiciously neat—is that it derives from a prolonged act of political nepotism. The Victorian prime minister, Lord Salisbury (family name Robert Cecil, pronounced ) appointed his rather less than popular nephew Arthur Balfour to a succession of posts. The most controversial, in 1887, was chief secretary of Ireland, a post for which Balfour—despite his intellectual gifts—was considered unsuitable. The Dictionary of National Biography says: “The country saw with something like stupefaction the appointment of the young dilettante to what was at the moment perhaps the most important, certainly the most anxious office in the administration”.
As the story goes, the consensus among the irreverent in Britain was that to have Bob as your uncle was a guarantee of success, hence the expression. Since the very word nepotism derives from the Italian word for nephew (from the practice of Italian popes giving preferment to nephews, a euphemism for their bastard sons), the association here seems more than apt.
Actually, Balfour did rather well in the job, confounding his critics and earning the bitter nickname Bloody Balfour from the Irish, which must have quietened the accusations of undue favouritism more than a little (he also rose to be Prime Minister from 1902–5). There is another big problem: the phrase isn’t recorded until 1937, in Eric Partridge’s Dictionary of Slang and Unconventional English. Mr Partridge suggested it had been in use since the 1890s, but nobody has found an example in print. This is surprising. If public indignation or cynicism against Lord Salisbury’s actions had been great enough to provoke creation of the saying, why didn’t it appear—to take a case—in a satirical magazine of the time such as Punch?
A rather more probable, but less exciting, theory has it that it derives from the slang phrase all is bob, meaning that everything is safe, pleasant or satisfactory. This dates back to the seventeenth century or so (it’s in Captain Francis Grose’s Dictionary of the Vulgar Tongue of 1785). There have been several other slang expressions containing bob, some associated with thievery or gambling, and from the eighteenth century on it was also a common generic name for somebody you didn’t know. Any or all of these might have contributed to its genesis.
