In the original novel, Mr. Brownlow is not a blood relative of Oliver, but is an acquaintance of Oliver's father, who gave him a portrait of Oliver's mother as a token of trust. Oliver, left for dead by Sikes after being wounded in a robbery, is rescued by members of his mother's family, who get in touch with Brownlow and puts it all together. Filming this subplot would have required hiring more actors and actresses and taking up time with explanatory dialogue, so it is much more convenient to have Brownlow be Oliver's grandfather, and reassign other characters' words and deeds to him.
John Howard Davies was only eight at the time, and child labor laws prohibited children under the age of thirteen from working in movie studios, but Sir David Lean managed to get around the restriction. Davies recalled that Lean "was unfailingly nice, unfailingly courteous. He used various devices on me. When I felt inhibited about doing something, he would often shoot the rehearsal. He wasn't silly enough not to do the take. But I pretty soon cottoned on to this because my hearing was even better than his, with his large ears, and I could detect the sound of a Mitchell turning over."
Cinematographer Guy Green also noted that the art direction presented some problems. "(Production Designer) John Bryan made it bloody difficult, too, although his sets were wonderful to photograph. He had Francis L. Sullivan as the Beadle going along a tunnel, and it was impossible to light it. So I gave Sullivan a lamp to carry with a light inside it which shone out into the tunnel, and that was it. Oliver was about grim, dirty interiors, and I used a lot of diffused light, something which has become fashionable now with color. I tried to get the effect of light coming through small dirty windows, and it had a kind of richness of its own."
In his search to find the perfect Oliver, Sir David Lean held an open audition at Victoria Palace in which he received around one thousand five hundred applications and interviewed all but eighty of them. Not one matched the image he had in mind for Oliver but in a stroke of luck, agent Ted Lloyd spotted the ideal candidate, John Howard Davies, at the home of an associate.
The character played by Betty Paul, "Singer at Three Cripples", was introduced as "Lucy Willow". At the time of the filming of this movie, Betty Paul was appearing in London as "Suzanne Valdis" in "Bless The Bride" (a role she repeated in BBC Sunday-Night Theatre: Bless the Bride (1956)), and in the same production, Elizabeth Webb took the lead female part of "Lucy Willow". This cannot be a coincidence, but has apparently never been commented on.
Even though Sir Alec Guinness had worked for Sir David Lean previously on Great Expectations (1946), Lean couldn't picture him in the role until Guinness convinced him to conduct a screentest. "He came on looking not far removed from what he looks like in the film", Lean remarked. "Of course I was bowled over by it and he got the part without another word."
Some insurance companies would not even cover Robert Newton, and the J. Arthur Rank Organisation wanted to boycott him, but Sir David Lean persisted, having worked with Newton previously on Major Barbara (1941).
The company that trained and supplied animals for film and television supplied the Staffordshire Bull Terrier for the role of "Bullseye" and also the Bull Terrier who played the role of "Bullseye" in the movie adaptation of Lionel Bart's musical "Oliver! (1968)".
When Sir David Lean first viewed the opening sequence, designed by Cinematographer Guy Green and Production Designer John Bryan, he stated, "We're going to have to retake this. It's too romantic. I want more edginess and more storm."
Working with Make-up Artist Stuart Freeborn, Sir Alec Guinness based Fagin's appearance on illustrations in the novel by George Cruickshank, which accented the character's wrinkles, baggy eyes, loose hair, bushy eyebrows, and beaked nose.