Of the 30 or so filmed versions of the same Charles Dickens novel (excluding indirect adaptations and parodies such as Oliver e sua Turma (1988)), this is considered the most complete and accurate adaptation, as it manages to depict almost all of the characters and incidents from the book.
From the newspaper date seen in Episode #1.5 (1985), and other signs and inscriptions throughout, it is established that the bulk of the story takes place in 1835 and 1836, ending the year before the novel started serialization. This also explains the scattered references to the King rather than the Queen who is more commonly acknowledged in Charles Dickens works. The King is William IV, who died in 1837 and was succeeded by his niece Queen Victoria, who began the Victorian age which lasted for the majority of the 19th century. England would not have a king again until the accession of King Edward VII in 1901.
This was the first job as a producer in television for Terrance Dicks, who was a very experienced writer and script editor. According to Dicks, the classic serial strand at the BBC was at the brink of being cancelled at the time by the new Controller of BBC One, Michael Grade, due to being expensive. According to Dicks, this serial was a big hit with viewers and achieved "record figures" on transmission, to such an extent that Grade decided to continue with it.