This excellent film is part of a duo of Dickens' books turned into silver screen magic by David Lean in the 1940s (Great Expectations with John Mills is the other).
Keeping to the spirit of the book (although not leaving the bleak ending intact) it allows us to follow the fortunes of young Oliver (John Howard Davies, who later gave up acting to become a big shot at the BBC), through his unhappy years at the orphanage under the watchful eye of the Beadle (the huge Francis L Sullivan, who played many similar roles throughout the decade), to his association with boy thieves under the thumb of Jewish money-dealer Fagin (Alec Guinness, in one of his career highlights).
The casting is generally superb - Kay Walsh (then Mrs David Lean) is effective as Nancy, while Robert Newton is suitably unhinged and menacing as Bill Sikes. In the undertaker's, Diana Dors is showy as Charlotte the maid; while in London, Anthony Newley makes an early scene-stealing Artful Dodger (like Jack Wild in the musical version, this Dodger isn't all bad and wants to make sure Nancy and Oliver are all right).
'Oliver Twist' is one of the greats of British cinema and does justice to a complex book. Highly recommended.