If you're talking Oz movies, this is the 800-lb gorilla. In fact it's been deemed the most watched film in cinema history, having been an annual TV tradition in America since 1959 except that these days it's broadcast before all sorts of holidays (Easter, Christmas, Thanksgiving, the 4th of July, etc.)

Oddly enough though, it wasn't very profitable at the time. It took three million at the box office, but making it had cost 2.8 million and it wasn't until its tenth anniversary re-release that MGM felt it had made any real profit. This was an expensive film. More precisely it was a lavish 1939 Technicolor production that was full of special effects and had five different directors. Richard Thorpe shot two weeks' worth of material, then got sacked for rushing things and hurting the actors' performances. None of that footage has made it into the final film, because Thorpe had Judy Garland in a blonde wig and "baby doll" make-up, overacting enough that the next director told her to tone it down and "be herself".

The original version of the film that got shown to test audiences no longer exists because it ran for nearly two hours. Movies half that length were commonplace back then. The editors cut a good fifteen minutes just to reduce the running time, but for once I suspect this might have been a good thing, since as far as I can tell we basically lost a bunch of songs. I'd happily watch them as DVD extras, especially Jitterbug, but I like the fact that the final movie eventually forgets about singing and just gets on with the plot. If nothing else, I'm fairly neutral about the songs. Oh, they're good enough. I don't object to them. "We're Off To See The Wizard" is probably my favourite of them, but "Somewhere Over The Rainbow" is a straightforward Aspirational Heroine ballad and I don't think it's some kind of musical holy grail just because it happened to win an Oscar. I'm not bashing this music at all, but personally I'd sooner listen to one of Disney's Ashman-Menken features, or indeed (obviously) The Wiz.

Oh, and the Munchkin sequence is deeply weird. You've got creepily dolled-up Little People on a raked set designed to make them look even smaller than they are already, singing at extraordinary length about the joy of death. Incidentally, were the three surly hooligans meant to be a parody of someone?

As an interpretation of L. Frank Baum's Oz mythology, it has eccentricities. I dislike it all being a dream, which does Baum a disservice and dissuades one from thinking of his Oz as an enormous, rich world in its own right. Dorothy falls into bed and closes her eyes, then eventually returns to Kansas by waking up again. That's one reading, anyway. You could squint around that and concentrate on the tornadoes and flying houses, but harder to explain away are Morgan, Bolger, Lahr, Haley and Hamilton all playing both ordinary Kansas folk and magical Ozzians. Margaret Hamilton we see transforming from one role into the other during the tornado sequence, but there's no such get-out available for the others. It's deliberate, obviously. Audiences in 1939 were thought to be too sophisticated for fantasy, despite the fact that MGM was only making Wizard of Oz in the first place because Walt Disney had just hit the jackpot with Snow White and the Seven Dwarves. Obviously this is nonsense, even in the Great Depression.

That said, though, it works. I dislike it on principle, but it improves the dramatic structure. The first twenty minutes in Kansas are basically a rerun of the entire film in miniature, in which Dorothy meets all her Oz friends (monochrome version), complete with knowing references to courage, a head full of straw and "you're a wicked old witch". She then runs away from home, but is persuaded to turn back by Frank Morgan, again playing a fraudulent so-called wizard. He claims that Auntie Em is worried sick and in tears, which of course horrifies Dorothy and so she's heading straight back when the movie hits her with a tornado.

This is brilliant because it gives Dorothy motivation. In the book, she just wants to go home. Why? Because she does. She's a child and that's what children want. Baum could get away with that, but it would have worn thin in a movie, especially with a Dorothy who's Judy Garland with her breasts obviously taped down and an all-singing, all-dancing Technicolor Oz. You'd want a strong reason to return to monochrome-land and that's Auntie Em. Furthermore we're not sad when she gets there, as opposed to the disappointment everyone feels at the end of any Beauty and the Beast movie. She hasn't abandoned her new friends because they're all in Kansas too! Dramatically this is clever and neat. Thematically though it's dodgy, with a message of "if you're looking for your heart's desire, don't go beyond your own backyard". In other words, peasants should know their place and stay put.

How does it compare with other Oz films? Answer: it's so different that it hardly even feels like the same genre, although to be honest that's true of all of them. There are similarities, of course. MGM bought the rights to the 1902 Baum-Titjen stage musical and to Larry Semon's 1925 feature film, so reusing the same actors between Kansas and Oz could at a pinch be regarded as coming from the Semon film. Similarly Glinda's poppy-killing snowstorm comes from the stage show. However if you're regarding it as the next generation after its silent-era predecessors, the biggest single difference for me was having an actor as the Cowardly Lion, as opposed to just having a panto (or real) animal. Until now he'd just been a special effect. Here though you've got Bert Lahr being... um, being a bit annoying, actually, but that's still a step forward. I'm not wild about Lahr. I'm not going to say he's bad and he's easily good enough for the film's requirements, but I do think the role had enough comic potential that another actor as the Lion could have stolen the movie. He's nowhere near as entertaining as Ted Ross in The Wiz, for instance.

Hmmm. I seem to have started talking about the cast.

Judy Garland's Dorothy is the weird one. She's almost jarringly one-dimensional, never saying or thinking a thing you wouldn't get from an eight-year-old. She feels less mature than Fairuza Balk in 1985 and I think Balk was playing down too. Nevertheless that said, Garland's completely solid in the role and successfully bringing this odd, skewed Dorothy to life, despite only being sixteen herself when she was cast. She won an Academy Juvenile Award that year for her work in two films: this and Babes in Arms. It's almost impossible to imagine how the film would have felt had the lead role gone to Shirley Temple after all. Of the supporting players, Frank Morgan is avuncular and sweet (in five roles!). Margaret Hamilton struck me as oddly mechanical in her first scene in Oz, but then again her work in the movie was generally felt to be too frightening for audiences and a lot of it got cut, so maybe the editor in that scene was deliberately using lesser takes? Hamilton was a fan of L. Frank Bam's, incidentally, and had been over the moon at getting the role.

One thing I did like was the Scarecrow, Tin Man and Lion's physicalities, by the way. I laughed at the Tin Man's slightly clumsy dance after being oiled, especially the head toot, while the Scarecrow's swinging arms are iconic enough that forty years later in The Wiz you'll see them getting imitated.

The coolest thing about the film is its 1930s three-strip Technicolor. In other words, the colour palette looks like a child's crayon set and Judy Garland has a bit of the characteristic "boiled salmon dipped in mayonnaise" look. On a normal human this looks odd, but on all the magical stuff it's brilliant. This Oz is freaky! Check out Glinda's teleportation bubble. Note also the bright green witch who materialises in a cloud of pillar-box red smoke and has an army of disturbing flying monkeys. They're blue with red lips. It's the kind of colour scheme you used to get in old comic books and for the same reason. Suddenly it makes complete sense that Baum's silver slippers have been changed to be ruby. Admittedly I wasn't wild about their Emerald City, which looks like a leprechaun theme park on St Patrick's Day, but I'd forgive almost anything though for the "horse of a different colour".

Then there's the monochrome sequences, which are a clever idea and oddly faithful to the book's description of Dorothy's home as grey. Even the transition between them is sophisticated, with mixed colour and monochrome shots like Dorothy stepping outside into Oz or Auntie Em appearing in the witch's crystal ball. However the monochrome isn't black and white, despite having looked like that for years on TV stations that had simply been turning off the colour signal. The traditional description of these scenes is "sepia", but a more accurate one is "ugly flesh pink".

It's a family film, obviously. However it's a 1939 family film, which can by modern standards make it look a little eccentric. Obviously it's less bloodthirsty than Baum. The Tin Woodman doesn't go around decapitating things and the Wizard only wants the witch's broomstick instead of ordering her death. No schoolgirl assassination squads here, thank goodness. However the melting witch was nasty at the time (as I remember my primary school teacher telling us) and I thought it was a bit weird and almost gruesome when the squashed witch's feet shrivelled up when she lost the ruby slippers. Cool. There are also some odd thematic implications and subtexts. I've mentioned one already, but others include "ugly people are evil", "look kids, narcotic poppies!" and "cowardice makes you effeminate and homosexual", although heartwarmingly the gay community seems to have embraced the latter as part of a big gay tapestry. Garland would become a gay icon, while for a more detailed reading I'm simply going to quote Cassell's Encyclopedia of Queer Myth, Symbol and Spirit. "Its emotionally confused and oppressed teenage heroine longs for a world in which her inner desires can be expressed freely and fully. Dorothy finds this world in a technicolor land 'over the rainbow' inhabited by a sissy lion, an artificial man who cannot stop crying and a butch-femme couple of witches."

The production values are solid. The talking trees are a bit obviously rubber, but the witch's army looks badass and her castle is like Lord of the Rings. However there are also some things we're clearly not meant to be thinking about, such as why the witch keeps a bucket of water in her castle in the first place. Also the scarecrow's mathematical formula at the end to prove his intelligence actually proves the exact opposite. The sum of the square roots of any two sides of an isosceles triangle will apparently equal the third side's... no, hang on a minute.

In summary, this is a deceptively clever film. It's turning something wildly episodic into a proper movie, for instance in its beefing up of both Dorothy and the witch. The latter only appears in a single chapter of Baum's original book, you know. Some of its apparent oddities are among its most interesting points, for instance in the way the Wizard's gifts to the Scarecrow, the Lion and the Tin Man are so blatantly just flam-flam that this becomes the whole point of the scene. It's about what's inside you. The Scarecrow had always been the one who was saying intelligent things, for instance. This isn't necessarily the film you'd pick as the one to have been seen by more people than any other ever, but in its own way it doesn't feel unworthy of the title either. You definitely shouldn't be dismissing it as vaudeville nonsense, as Disney did when building up Return to Oz. It's far more than that.