"Bob's your uncle" is a saying that originated in England and is in use throughout the former British Commonwealth countries, including Canada. The phrase means "there you have it" or "simple as that." It generally is used to emphasize how easy something is to do. For example, when asked how to change a light bulb, someone might reply, "Unscrew the old light bulb, screw in the new one, and Bob's your uncle." The origin of this phrase is unclear.
One theory of this phrase's beginnings is based on the perceived political nepotism of 19th century English Prime Minister Robert Cecil, Lord Salisbury. He appointed his nephew Arthur Balfour to a succession of government posts for which others were seen as more qualified. The theory is that in the popular culture of the time, an irreverent view arose that having Robert Cecil — Bob — as one's uncle was a guarantee of success. A problem with this theory is that the phrase "Bob's your uncle" is not known to have appeared in print until 1932 even though political satire and commentary had long been a staple of English publishing.
Another theory proposes that "Bob's your uncle" refers to the English military commander Frederick Roberts, 1st Earl Roberts. Roberts was one of the most successful military leaders of the latter 19th century in Asia and Africa. He was highly regarded by his troops, who nicknamed their commander "Uncle Bobs." According to this view, the phrase developed among the rank and file of Roberts' army to boost morale and imply that all would be well and all endeavors successful under his command. As soldiers completed their tours of duty and returned home, the expression would have traveled with them to all parts of the British Empire.
It also has been suggested that the phrase might have derived from earlier idiomatic expressions such as the 18th century English slang "all is bob," meaning that all is well or as it should be. There are numerous English sayings containing the word "bob" that predate the common usage of "Bob's your uncle." Bob was also commonly used as a generic name in examples or in referring to a person whose name was unknown. Given the fluid state of popular culture, the dozens of different English dialects and the changing meaning of idioms, it is unlikely that the phrase will ever be directly attributable to any single person or group.