You may or may not have heard of The Private Life of Sherlock Holmes (1970). Mark Gatiss, writer of BBC's hit Sherlock (2010) loves it: "it is a fantastically melancholy film," he says for the Guardian. "It was a template of sorts for Stephen Moffat and me as we made our adaptation for the BBC."

Warning: spoilers ahead.

The film follows Holmes and Watson through two essentially unconnected cases - the first, where they receive a mysterious invite to Swan Lake, wherein Holmes is propositioned by a retiring Russian ballerina. In the second, they are visited by an amnesiac dame in distress (Gabriela), who informs them of her missing husband. From there, they take a trip to the Scottish Highlands to uncover an international conspiracy.

The Private Life of Sherlock Holmes

Holmes (Robert Stephens) & Watson (Colin Blakely)

Though the second story is fun and rather takes the mick out of Holmes - in a very good humoured, I-love-you-really kind of way - the first story is far, far more interesting. And to me, what's fascinating about The Private Life is not what it is, but what it was trying to be, and why it didn't end up like that at all.

The movie tackles something often pondered about Holmes; his romantic and sexual relationships, or lack thereof. Many have theorised Holmes to be gay, asexual, celibate, straight, or in a category unto himself. Gatiss says this: " The relationship between Sherlock and Watson is treated beautifully; Sherlock effectively falls in love with him in the film, but it's so desperately unspoken."

And this, most strange of all, is not debunked or ignored (as these sorts of claims often are) by the scriptwriter and director Billy Wilder. In fact, he even expressed remorse for not just getting it over with and portraying him as gay. No big budget film has ever portrayed Holmes as anything other than straight or suspiciously celibate, and in the 70s (and possibly even now... will anyone dare make the leap?), it would have been simply impossible to get past the studio executives, so it's not odd that Wilder didn't.

So The Private Life is a decidedly odd juxtaposition. In the first half-hour, it roars ahead with what looks like a promising take on sexuality in the 1890's...

But by the end, it's a classic Holmes, Watson, and woman tale.

To be fair, The Private Life suffered some serious meddling. Half of the original movie (intended to be 4 individual plots) was cut due to studio insecurity over the poor performance of other roadshow films released that year. Roadshow films were three or four hours long and had a break for concessions, but instead, the film was reduced to a normal running time. These missing scenes are forever on the cutting room floor, lost the brutal butchering of the original cut; some have been recovered partially in audio or visual, but rarely both.

The scenes play an intrinsic part in explaining Holmes, and his relationship with Waston. A flashback wherein Holmes describes how he was tricked into seeing a prostitute while at university was cut, but it explains his mistrust and insulting opinions of women throughout the film (for those of you who know the film, this scene lays while Holmes and Gabriela talk on the night train to Scotland). But it has to be asked - Did Holmes recount this in order to rebuff Gabriela, who's fancy she takes? Or because it was true, and that he was more of a man scorned?

This doesn't really fit in with Wilder's wanting to make Holmes gay; why have this scene in the script at all? Perhaps it was supposed to be a continued exploration of Holmes' ever elusive sexuality. Perhaps to Wilder, the prostitute was never supposed to be female, but just defaulted that way. Or, perhaps it never occurred to get rid of these scenes until it was too late. It cannot be said for certain.

The Private Life of Sherlock Holmes attempts to be many things, but fails to be little more than a classic Holmes' story riddled with melancholy, supported by Robert Stephens' fantastically harrowing but delicate performance. Throughout, the feeling that something just isn't finished plagues - be it a resolution to Holmes' drug use, his relationship with Watson or Gabriela, or indeed, with women as a whole, the story isn't quite done. But if you haven't watched it and got this far, I'd still suggest you do. If you can, get your hands on a copy of the original, uncut script (it's out there if you look for it) to compare with the final product.

And really, The Private Life of Sherlock Holmes is quite the ironic title. Because just as we think we've started to understand Holmes, he shuts the door on us, just like he does to Watson in this beautifully written scene.