From its launch in April 1964, BBC2 began each evening's transmission with a programme called Line-Up, a ten-minute collection of reviews and previews of the channel's output, presented initially by Denis Tuohy.
It never happened, but the freedom for discussion, without worrying about exceeding the broadcasting day allowance made the programme very popular, especially with those who enjoyed watching television late at night, as BBC One and ITV generally closed down by 11.45 p.m. each weeknight.
Late Night Line-Up eventually went well beyond its initial remit of examining BBC2's output and came to incorporate interviews, live music and poetry performances and discussions of other TV channels (which meant ITV to all intents and purposes) and even current affairs issues.
Presenter Tuohy quotes the then head of Light Entertainment, Tom Sloan, as saying: "We now employ two kinds of broadcaster: those who make programmes and those who knock them.... Don't ask me why we do it."
[1] Presented by Joan Bakewell, it featured discussion of the themes and programmes shown over the course of the evening and examined the liberalising legislation passed by Parliament in the late 1960s.