What is the origin of the phrase 'Bob's your uncle'?

it goes back to the 1880's when Lord Salisbury, the Prime Minister gave a political job in Ireland to Arthur Balfour. Lord Salisbury was known to Arthur Balfour as 'Uncle Bob'. Lord Salisbury had given a job to a member of his family. The public became aware of this so the words 'Bobs your Uncle' became a sarcastic comment. Later when the words passed into common usage in the English language they came to mean "you've got it made - easy - that's great"