McClef, Inheritance might have survived since it was in independent broadcasting production.

For those not in the know, the BBC did not archive TV programs until the late 60s-early 70s on the basis that they didn't want to waste video/audio tape. Many classics were lost from this period: in particular work by Peter Cook and Dudley Moore. It was common UK television practice at the time, when agreements with actors' and musicians' unions limited the number of repeats. This policy ceased in the late 1970s.