First BBC2 drama to be made in colour.
Fourteen episodes of this series are missing from the archives.
Marius Goring's future (third) wife, Prudence Fitzgerald, directed him in 18 episodes of the series.
Most of the original master tapes of 'The Expert' were wiped by the BBC. Although many episodes were later recovered on 16mm film, only one episode from the first series remains in the archives; the vast majority of series two and three also remain, and series four is complete.