Used to describe the means of straightforwardly obtaining a successful result.
The expression is often said to derive from the supposed nepotism of the British Prime Minister Lord (Robert) Salisbury, who appointed a favourite nephew, Arthur Balfour, to several political posts in the 1880s. Balfour had considerable talents and went on to become Prime Minister himself, but his early political appointments were considered inappropriate as he showed no interest in public work and at the time preoccupied himself with philosophy and an active social life. It is unlikely that Arthur Balfour would ever have become a celebrated politician without the patronage of his influential uncle.
A second interpretation has that it the phrase derives from the slang term 'all is bob', meaning 'all is well'.
The slang word 'bob', with the 'shoplifter's assistant' meaning, had been in circulation for some years at that time and is defined as such in Nathan Bailey's .
The third potential source is in a music hall song written by John P. Long, and published in 1931.The song was sung and recorded by Florrie Forde, the celebrated music hall artiste of the early 10th century.
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