The actor will play Fagin in Dodger, a period family comedy series set to air next year.
Billy Jenkins takes the title role of The Artful Dodger, with the star cast also including David Threlfall as the police chief, Saira Choudhry as Nancy, Frances Barber a theatrical dame, and Tanya Reynolds as Queen Victoria.
Thomas is co-directing the series, which is now being filmed by NBCUniversal International Studios in and around Manchester, with Hildegard Ryan. One of the ten episodes has been guest-written by Charlie Higson.
The BBC explains: "A funny, optimistic, fast-paced comedy drama full of jeopardy, there are some familiar characters and a whole gallery of colourful, new ones. Each episode is a standalone adventure brought together at the end of the series with some dramatic reveals and surprises.
"Dodger follows the exploits of the infamous pickpocket, The Artful Dodger, and Fagin's gang as they find ingenious ways to survive the grim and exploitative conditions of early Victorian London in the 1830s.
"The group of young misfits is led by Dodger and his pickpocketing partner-in-crime, Charley Bates, a girl from the countryside with a mysterious past. They are joined by Polly, Tang and Dodger's adversary in the gang, Tom. Together the orphans duck and dive their way through the criminal underworld, trying to make a better life for themselves, whilst satisfying Fagin's pickpocketing demands and avoiding the hangman's noose. The police are always just one step away with Sir Charles Rowan becoming increasingly obsessed about how to deal with the gang and catch Dodger."
CBBC also today announced the commission of ten-episode musical series Nova Jones. The sci-fi sitcom follows an 18-year-old pop star and her 12-year-old sister and manager "as they go on a concert tour throughout the galaxy". Already filmed in Belfast by JAM Media, the comedy is now in post production for "high-end CGI and visual effects", and will air later in 2021.