The character played by Betty Paul - "'Singer at 'Three Cripples'" was introduced as 'Lucy Willow'. At the time of the filming of "Oliver Twist", 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 leading female part of 'Lucy Willow'. This cannot be a coincidence but has apparently never been commented on.
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 film adaptation of Lionel Bart's musical 'Oliver!'.
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 put it all together. Filming this subplot would have required hiring more actors 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.