Julian and Sandy were two camp, out-of-work actors, who were always at work in a franchise that featured the word bona, which means 'good' in Polari.
Polari was gay slang used as a secret underground language before the decriminalisation of homosexuality in Britain back in the 1960s.
They could be found working at such ventures as Bona Promotions, the Ballet Bona, Bona TV Ltd, and Polari Vous Francais: the Bona School of Languages.
As well as being highly amusing, Julian and Sandy were notable for being two camp homosexual characters in mass entertainment at a time when homosexuality was still illegal in the UK, and for the use of Polari in the sketches.
The writers and cast thought the characters worked very well as they were not being held up to ridicule or simply there to be the target of a joke, in fact most of the sketches revolved around Kenneth Horne's presumed ignorance being the target of their jokes.
Kenneth Horne would find these two characters usually by looking in a rather risque magazine (which he would insist he bought for innocent reasons). This would lead him, more often than not, to their business in Chelsea.