Douglas Wilmer was infuriated when he first received some of the scripts for the series. He said that the dialogue ranged from being acceptable to downright deplorable. As a result, the actor spent many hours into the night at home, re-typing most of the scripts. The actor stated that the officially credited writers, hadn't bothered to carry out their research, regarding the Holmes stories in general.
Douglas Wilmer later recalled that Peter Cushing told him he would rather sweep Paddington station for a living than go through filming this series again.
Practically all of the first series survives intact: the concluding reel (approximately the final 20 minutes) of The Abbey Grange (1965) and the opening 25 minutes (plus the full soundtrack) of The Bruce-Partington Plans (1965) are the only known existing extracts from those stories. The second season fares far worse, with only A Study in Scarlet (1968), both parts of "The Hound of the Baskervilles", The Boscombe Valley Mystery (1968), The Sign of Four (1968) and The Blue Carbuncle (1968) still known to exist. In 2019 brief extracts were discovered from The Second Stain (1968), The Dancing Men (1968), The Naval Treaty (1968) and Black Peter (1968), whilst a largely complete soundtrack for The Solitary Cyclist (1968) has also been recovered.
The second series was one of the earliest BBC colour productions.