The Private Life of Sherlock Holmes is a 1970 DeLuxe Color film in Panavision written and produced by Billy Wilder and I.

In the main plot, a Belgian woman, Gabrielle Valladon, is fished out of the River Thames and brought to Baker Street.

It turns out that Sherlock's brother Mycroft is involved in building a pre-World War I submarine for the British Navy, with the assistance of Monsieur Valladon.

When they meet, Mycroft informs Sherlock that his client is actually a top German spy, Ilse von Hoffmanstal, sent to steal the submersible.

In the final scene some months later, Sherlock receives a message from his brother, telling him that von Hoffmanstal had been arrested as a spy in Japan, and subsequently executed by firing squad.

[5] The hefty British actor James Robertson Justice was offered the role of Mycroft Holmes but refused to shave off his beard.

[5] Lee was eternally grateful to Wilder for allowing him to take the part since it helped his career and he was able to end being consigned to horror movies.

Based on numerous clues, Holmes deduces that the man is an Italian music teacher who was having an affair with the wife of a nobleman, got caught, jumped out the window, and ran onto the train.

(Only the audio for this sequence survives, along with production stills) - "The Adventure of the Dumbfounded Detective" - During the scene in the film where Holmes is traveling by train to Scotland with Gabrielle, there was originally a segue into a flashback, where he told her about his student days at Oxford.

After Holmes's crew team won a race against Cambridge, to celebrate, they pooled their money and held a lottery, with the winner getting time with a prostitute (Jenny Hanley).

(This scene is entirely lost, only production stills and the script survive)[7][8] - "The Dreadful Business of the Naked Honeymooners" - As Holmes and Watson travel back to England on an ocean liner, having solved a case for the Sultan in Constantinople, Holmes complains that anyone could have solved the case, even Watson.

Holmes watches, without saying anything, as Watson proceeds to go to the wrong cabin, where he finds a honeymooning couple (Nicole Shelby and Jonathan Cecil) passed out drunk, naked, in bed.

Mistaking them for the murder victims, Watson begins to deduce an elaborate solution based on the "evidence" he sees around him, while Holmes listens, amused.

[5] (Only the film footage for this sequence survives, the audio is lost) - An epilogue scene, immediately after Holmes retreats into his room to use cocaine on learning of the death of Gabrielle/Ilse, in which Inspector Lestrade arrives at 221B Baker Street and asks Watson for Holmes's help in solving the ongoing Jack the Ripper murders.

[10] Director Billy Wilder has said he originally intended to portray Holmes explicitly as a repressed homosexual, stating, "I should have been more daring.

[13] Vincent Canby called it a "comparatively mild Billy Wilder and rather daring Sherlock Holmes, not a perfect mix, perhaps, but a fond and entertaining one".

[15] Kim Newman, reviewing it in Empire magazine, described it as the "best Sherlock Holmes movie ever made" and "sorely underrated in the Wilder canon".

He wrote that it is "disappointingly lacking in bite and sophistication", that it "begins promisingly enough" but that "before the movie is 20 minutes old, Wilder has settled for simply telling a Sherlock Holmes adventure".

[17] Gene Siskel gave the film one-and-a-half stars out of four and called it "a conventional and not very well written mystery" that made it seem as though "Wilder had enough of an idea for a television variety show skit but unfortunately saw fit to expand it into a movie".

[18] Charles Champlin of the Los Angeles Times wrote that "the whole effect of the picture is a kind of affable blandness which, given the expectations you have of Billy Wilder, constitutes a disappointment".

[21] In 1994, Image Entertainment released the film on LaserDisc, in what was called Private Life of Sherlock Holmes, The: Special Edition.