Each episode was rehearsed for two weeks.
Donald Wilson gave up his position as Head of BBC Serials in 1965 so that he could concentrate all his efforts on making this serial.
Apart from the credits and occasional tunes from the background, there is absolutely no music score in the whole show.
If Eric Porter had not played Soames the next choice would have been Bernard Kay.
The end titles credit Marcus Dods for music, but he only conducted Eric Coates' (non-original) theme music. This was "Halcyon Days", the Elizabeth Tudor opener of Coates' "The Three Elizabeths Suite" from 1944.