The Bill Oddie song in question appears in episode 8 of the 1968 series - look out for the priceless El Budgerigar sequence in the same show (that is, if the b******s haven't decided to broadcast the World service transcription edition instead, which omits some items).
However, I don't know which series of ISIRTA is being re-broadcast on 7 at the moment, and have no DAB radio so I can't hear it... most frustrating...