Most of the episode is set at Oldacre's home. One property was used extensively for filming: the interior, exterior, garden, driveway and road outside. It was Beech Mount, Bowdon Road, Altrincham, Greater Manchester.
This episode sees the first appearance of Colin Jeavons as Inspector Lestrade. Michael Cox, producer of the series, stated that Jeavons was the best Lestrade of his generation.
In conversation with Holmes at the start of the episode, Dr Watson refers to "...the case of the papers of ex-President Murillo, and also the shocking affair of the Dutch steamship Friesland, which so nearly cost us both our lives." Both of these are untold stories of Conan Doyle's.
Sir Arthur Conan Doyle's original short story The Norwood Builder describes Jonas Oldacre as "a strange little ferret-like man". The actor who plays him here, Jonathan Adams, was, on the other hand, a tall thick-set person.
Helen Ryan plays Mrs McFarlane and was to appear in a later episode, The Mazarin Stone, as the Princess of Wales.