online catalogue of BBC programmes which has info on over 900,000 BBC radio & TV programmes broadcast from as long ago as 1937. The database is updated daily. (More info on the prototype).
While the back catalogue is not fully comprehensive and you can't download the programmes themselves, you can search to see what was aired when, and see some of the details of the programmes, e.g. did you know there were 4096 programmes of Blue Peter between 1958 and 2006, 755 programmes of Dr Who in 1963-2006, 27 programmes of the Clangers between 1969 and 1974, and that the Singing Ringing Tree was first broadcast on 19 November 1964? There are even feeds offered for some items.
(Via Creative Archive.)