Wikipedia expresses some reservations about the reference to Bob being Lord Salisbury simply because the expression 'Bob's your uncle' did not appear in print until 1932. The author has forgotten that the man whose uncle Bob ,Lord Salisbury, was, Arthur Balfour did not die until 1930. He coud sue for the libellous innuendo in the phrase , which is patently referring to him. Every appointment he ever held, from the first , secretary, to his last- but- one was an appointment by his uncle.For the last, Prime Minister he was his uncle's appointed successor , recommended by his uncle..
The right to sue for libel dies with the persond libelled. so after 1930 there was no risk of being sued for this one .