What is the origin of calling the BBC "Auntie Beeb" ?

The audience in the 1930s was some 40 - 50% of the adult population and to address this enormous listenership a more informal style in talks and continuity developed than in the 1920s. The Corporation was, however, often criticized by the press as arrogant, snobbish, smug, and overly eager to educate the public, whence in the early 1960s its equivocal nickname Auntie. The informal and usually affectionate acronym the Beeb (from the beginning of 'bee-bee-cee') emerged somewhat later. The two are sometimes combined as Auntie Beeb, while for the BBC in Scotland MacBeeb is sometimes used.