Not Going Out anytime soon

Tonight on BBC1 a special live edition of the Sit-Com Not Going Out is being shown. The show has been going out since 2007 and has on one occasion survived he axe. Though never a spectacular ratings hit in the manner garnering a viewership of around 5 million viewers. So how did it survive the axe? It is said that DVD sales of the show were so large that the cancellation of the show would mean a large loss of income for the BBC!