Answer: A British Prime Minister

A common phrase in British English, and used by families with British and Commonwealth ancestry in other countries, is “Bob’s your uncle”. The phrase is roughly equivalent to the American phrase “piece of cake” and implies that whatever instructions you were just given or whatever the odds in front of you are, things will be easy.

While “piece of cake” seems to have a pretty straightforward etymology—eating a piece of cake is easy and pleasurable after all—“Bob’s your uncle” is a rather odd, and seemingly intimate, turn of phrase. Who is Bob, after all? What bearing does him being your uncle have on the ease of something?

A lot, it turns out, if your uncle Bob is the Prime Minister of the United Kingdom that is. Back in 1887, then sitting Prime Minister Robert “Bob” Cecil appointed his nephew, Arthur Balfour, as the Chief Secretary for Ireland. The move both surprised the public and the general attitude was that whatever qualifications the young politician had, the most important one was that Bob was his uncle. The whole event apparently made enough of an impression that “Bob’s your uncle” has persisted, for a century and change, as a British idiom.