Of the five extant full-length features based on Charles Dickens's Oliver Twist (among which I include the 1968 musical), this 1948 version is often considered the yardstick against which all others are measured. It's said that comparisons are odious, but it's necessary to examine it in relation to the other four to reveal why it is so highly regarded, as well as to some extent debunk its revered status.

First, we must begin by acknowledging that Dickens's book is a great but somewhat flawed work. It may be considered bad form to even think of criticising an undisputed genius, but bear in mind that this was only his second novel, and he was a young and inexperienced writer. Oliver Twist's strength lies in its larger-than-life characters, sparkling dialogue and imaginative set-pieces, but structurally it has some huge problems. This is why, throughout all the screen versions, depictions of figures such as Mr Bumble, Fagin and Bill Sykes differ very little, key scenes such as asking for more or the handkerchief stealing game are staged similarly, but there are many variations as to the overall plot. While the versions made in 1922 and 1933 are faithful if rather pared-down adaptations, the screenplay by David Lean and Stanley Haynes was the first to do the unthinkable and rewrite Dickens.

Probably the most drastic and for me the most necessary difference between this picture and the novel is Oliver's fate after he is forced to accompany Bill Sikes on the burglary. In the novel he is wounded and taken in by the family whose house it is. However, Lean and Haynes do not show the burglary, and keep Oliver in the custody of Fagin and co. until the finale. This is a vast improvement, as it means Oliver remains in real danger throughout the last act, and adds extra motivation to the race to bring the criminals to justice. So crucial to the impact of the picture was this change that it was used again for the 1968 musical and Roman Polanski's 2005 effort, and the image of the young hero clambering over the rooftops with Sikes urging him on is now established in the public conscious.

However there is one problematic way in which the 1948 film deviates from all the other versions, and that is in the size of Nancy's role. She is introduced fairly late, after Oliver's arrest, and she gets precious little screen time before being murdered. Significantly, her fondness for Oliver is not developed; she never even speaks to him, and consequently it seems odd when suddenly steps in as his protector. She is not even portrayed especially sympathetically, and as a result her death is not the blow to the audience that it should be. To me, the character of Nancy is the key to the whole thing; she is a surrogate mother (or big sister) figure to Oliver before he finds his real family, and her brutal murder is the biggest wrench of the story. Even the 1933 version, which otherwise has all the sophistication of a school play, recognises this.

The 1948 version at least looks great thanks to superlative cinematography by Guy Green, and of course the direction of David Lean. This picture is often praised for its harsh and grimy portrayal of Victorian England's underbelly, and Lean loads every frame with tone and character. He often throws in shots with no actors, which do not contribute directly to the story but add atmosphere to the scene. This kind of shot was by and large a no-no in Hollywood at the time, and for good reason because it can be a distraction, but Lean gets away with it because he does it so well. A great example is the series of storm shots from the opening scene, the best of which is a shot of two thorny stems twitching in the wind, instantly forcing us to think of physical pain, after which we cut to Oliver's mother in agony. The effect is more powerful than would be the shot of her alone. My only complaint with Lean's direction is his tendency to over-direct the low-key scenes, such as the one of Mrs Bumble setting about her husband, which is shot in the same manner as Oliver's assault on Noah Claypole, but as a scene it deserves far less weight.

And then we come to the actors. Aficionados of classic British cinema will understand that no-one but Robert Newton could have played Sikes in this production, and he's at his eye-rolling best here, although not as scary as Oliver Reed was in 1968. Kay Walsh is passable, but isn't right for Nancy, and her casting probably has something to do with who her husband was. Alec Guinness's Fagin has been denounced as anti-Semitic; in fact it goes right through anti-Semitism and out the other side. This caricature, with the unfeasibly massive nose and beard flapping around like a bit of old carpet, is simply ridiculous. True, Fagin is supposed to be a comedy character (and to his credit Guinness does ham it up funnily), but Oliver Twist is not a farce, and that over-the-top make-up is all wrong.

Through successive stage and screen versions, the story of Oliver Twist has continued to evolve. The musical eliminates the subplot with Monks, and the 2005 picture even goes as far as to remove the coincidence of Oliver being related to Mr Brownlow. This 1948 adaptation deserves credit for making this process of refinement acceptable, which is ironic as in spite of its break with tradition (and its flaws) through its tone and character it is probably the closest in spirit to the original text.

Over seventy years on and this version of 'Oliver Twist' is still garnering ecstatic reviews. There are a handful of gainsayers to be sure but their opinions are quite frankly inconsequential as this is simply film-making of the highest quality.

By all accounts it was Kay Walsh who came up with the idea for the astonishing opening scene which sets the tone for the whole film. Lean himself relates the amusing tale of how they utilised a stuffed cat in order to get the required reaction from the lethargic beast playing Bullseye during the effectively staged murder sequence. Necessity is the mother of invention! Film is of course a collaborative medium and Lean, no mean 'cutter' himself, has the services of one of the best editors in the business, Jack Harris. Behind the camera is Guy Green who had previously replaced Robert Krasker on 'Great Expectations'. This also represents the only full-length film score by Arnold Bax.

Too much of course has been made of the so-called anti-Semitic portrayal of Fagin by Alec Guinness. He and Lean both had the courage to stick to their guns by having the character resemble the original illustrations of George Cruikshank. In the immortal words of Columbia's Harry Cohn: 'the trouble is that accent and that schnozzle'. Ironically the film was banned in Israel for its anti-Semitism but banned in Egypt for showing Fagin too sympathetically! Mention must be made of the fabulous Robert Newton as Bill Sykes whose 'careful' handling is a testament to Lean's directorial skills. Henry Stephenson is perfect as Brownlow, Kay Walsh heart-rending as Nancy and Francis L. Sullivan as Mr. Bumble gets to deliver one of the author's most immortal lines: 'the Law, Sir, is a Ass'. John Howard Davies has been criticised by some for being a bit 'twee' as Oliver but the role could not have been played any better.

All of Lean's hallmarks that he was to exhibit on a far wider scale and with considerably larger budgets are in evidence here. A truly great version of a literary masterpiece is surprisingly rare in film as there seem to be so many 'compromises' but this is a glorious exception.