Practically all of the first series survives intact: the concluding reel (approximately the final 20 minutes) of Sherlock Holmes: The Abbey Grange (1965) and the opening 25 minutes (plus the full soundtrack) of Sherlock Holmes: The Bruce-Partington Plans (1965) are the only known existing extracts from those stories. The second season fares far worse, with only Sherlock Holmes: A Study in Scarlet (1968), both parts of "The Hound of the Baskervilles", Sherlock Holmes: The Boscombe Valley Mystery (1968), Sherlock Holmes: The Sign of Four (1968) and Sherlock Holmes: The Blue Carbuncle (1968) still known to exist.

The second series was one of the earliest BBC colour productions.

Producer William Sterling was keen for the second series to take its cue from the works of Alfred Hitchcock, advising his directing team to view Psycho (1960) to gauge the tone he wanted the stories to take.

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.

The 1968 episode "A Study in Scarlet" doesn't include any reference to the introduction of Sherlock Holmes and Doctor Watson, or how they came to be acquainted with one another. Instead, the episode begins with Holmes and Watson going about their usual business, plus giving the strong impression that they have known each other for years.

What was effectively the pilot episode of the series, Sherlock Holmes: The Speckled Band (1964), originally aired as the eighth edition of the first series of Detective (1964), an anthology of popular sleuths. Following this the BBC bought the rights for two series-worth of Holmes stories from the Doyle estate.

After Douglas Wilmer declined to star in the second series, the BBC asked John Neville to reprise his leading role from A Study in Terror (1965), with the same result. Next (and final) choice Peter Cushing had played the part in The Hound of the Baskervilles (1959) for Hammer, and would later reprise it in Sherlock Holmes and the Masks of Death (1984).

Both Douglas Wilmer and Peter Cushing were avid Sherlock Holmes enthusiasts.

Douglas Wilmer later stated that the series was riddled with incompetence and the scripts often came in late. He claimed that the scriptwriters ranged from "the brilliant to the absolutely deplorable." Some of the scripts were so lacking in quality that Wilmer himself rewrote them sometimes staying up until two o'clock in the morning rewriting.

Plans for celebrity villains such as Peter Ustinov, George Sanders and Orson Welles were abandoned due to budget constraints.

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.

Douglas Wilmer played author Jacques Futrelle's Holmesian detective Professor Van Dusen in The Rivals of Sherlock Holmes (1971) for ITV. He once again appeared as Holmes (albeit in a supporting role) in The Adventure of Sherlock Holmes' Smarter Brother (1975), with Thorley Walters as Dr. Watson.

Douglas Wilmer refused to return for a second series when he was told the rehearsal schedule would be cut.

This is the second time that Peter Cushing played Sherlock Holmes. He had previously starred in The Hound of the Baskervilles (1959) and would later star in Sherlock Holmes and the Masks of Death (1984).

After shooting of the two-part adaptation of The Hound of the Baskervilles ran over schedule and over budget due to persistent rain during location shooting, the second series once again fell victim to the time and money problems that plagued the first.

Peter Cushing stated that the hectic schedule affected his performance: "Whenever I see some of those stories they upset me terribly, because it wasn't Peter Cushing doing his best as Sherlock Holmes - it was Peter Cushing looking relieved that he had remembered what to say and said it!"

In spite of the various behind the scenes problems and tensions, this BBC TV production is usually credited as being the first attempt at producing a faithful rendition of Sherlock Holmes.

After voicing his anger and dissatisfaction with the low quality of the writing and taking matters into his own hands, Douglas Wilmer was informed that he was viewed as a troublemaker by the BBC.

Following his decision to leave the series after the first season, Douglas Wilmer vowed that he would never again work for the BBC.

The two part adaptation of "The Hound of the Baskervilles" is seen as being more accurate in the depiction of the plot in general.

Eric Porter was considered to replace Douglas Wilmer as Sherlock Holmes. While Porter ultimately did not get the role, he did portray Professor Moriarty opposite Jeremy Brett's Holmes in The Adventures of Sherlock Holmes (1984).

Had this third series commenced, the plan was to dramatise stories from The Exploits of Sherlock Holmes, a short story collection written by Adrian Conan Doyle and John Dickson Carr.This potential third series never came to pass.