The dream cast of the upcoming "Mary Poppins" sequel is almost complete. Oscar-winning actor Colin Firth has been added to the very British cast that makes up the upcoming Disney film.

Firth is set to play William Weatherall Wilkins, president of Fidelity Fiduciary Bank, Variety reported. "Mary Poppins" fans have been quick to speculate that Firth's William character might somehow be related to Dick Van Dyke's character, Fred.

Firth was recently seen in the movies "Bridget Jones' Baby" and "Genius." He's next appearance will be in "Kingsman: The Golden Circle," in which he reprises his role as the dashing and suave spy Harry Hart.

The 56-year-old actor joins the stellar "Mary Poppins" sequel cast list that includes Emily Blunt, Meryl Streep, Emily Mortimer, Ben Whishaw and Lin Manuel-Miranda. Blunt is billed for the titular role, which was made famous by Julie Andrews in 1964.

Blunt reveals in an interview with EW that she received blessing from Andrews for the role. "I feel a little more trepidation with this [character] because she's so emblematic of people's nostalgia," Blunt said about stepping into the shoes of the iconic character.

Streep is playing Mary Poppin's cousin, Topsy, while Mortimer and Whishaw will play siblings Jane and Michael Banks.

The "Mary Poppins" sequel takes place two decades after the events in the original film. Jane and Michael Banks are now grown-ups, with Michael having three children of his own. A tragedy reunites them with Mary Poppins, who brings back joy and adventure in their lives.

According to Blunt, the upcoming film will focus more on the books, which showcases a different version of Mary Poppins as compared to the magical nanny seen in the original 1964 film. Blunt teases that her version of Mary Poppins is "a little meaner."

"Mary Poppins Returns" will be helmed by Rob Marshall. The screenplay will be written by David Magee, and will be based on eight-part "The Mary Poppins Stories" book series by P.L. Travers. Marc Shaiman is in charge of the musical score together with Scott Wittman.

"Mary Poppins Returns" will soon hit theaters on Dec. 25, 2018.