William Weatherall Wilkins is the main antagonist of Mary Poppins Returns. He is the current president of the Fidelity Fiduciary Bank and the nephew of Mr. Dawes Jr. While Wilkins acts polite and charming when we first see him, he is actually a ruthless and corrupt corporate executive. This is represented in the Royal Dalton Bowl, where his counterpart is a wolf who pretends to be as docile as a lamb, signifying how he is a metaphorical "wolf in sheep's clothing".
Wilkins drives the main conflict of the film, as he seeks to repossess the Banks family home, to the point of burning important records left by George Banks that would have saved the house. He is using advantage of the Great Depression to repossess people's houses, for pretty much no reason.
Wilkins first appears about 30 minutes into the movie, when Michael Banks and his sister Jane come to talk with Wilkins about locating their father's shares in the bank. Wilkins, feigning sympathy, pretends that he has no record of their father on file. But he tells them that they have until Friday at Midnight, to repay their loan or locate the shares certificate. After they leave, Wilkins reveals his true nature by revealing the file of George Banks, tearing it up and throwing it into a fire to destroy any evidence of the shares.
One day, Wilkins is talking to his attorneys, who inform him that the bank has repossessed 19 houses within a week. While congratulating them for their work, Wilkins informs them of his plan to repossess the Banks' house even if they prove their shares, and the Banks' children overhear him and his plan. They immediately chase the children to Michael where Wilkins denies it, and Michael orders Mary Poppins to take the children home.
On Friday night, Wilkins is at the bank, counting down the time before midnight. Just when Big Ben is supposed to ring at midnight, Wilkins is perplexed as to why it is not ringing and the attorneys inform him that Big Ben's lights are out. Even though his watch chimes at midnight, Big Ben doesn't fire up again until after midnight and it gives Michael and Jane an extra 10 minutes to reach the bank and prove their shares. Upon seeing the Banks family arriving, Wilkins has his attorneys rush downstairs to lock the door. However, he suddenly sees a kite fly into his office and, soon afterwards, the Banks family, Jack, and Mary Poppins reach the room where they tell Wilkins they located the certificate.
Upon watching the Bankses' put the certificate together, Wilkins informs them that they are missing the piece of the certificate with George's signatures all over it, and Wilkins is about to claim victory, when suddenly, his uncle, Mr. Dawes Jr. arrives into the room. Tired of how morally bankrupt Wilkins is, Mr. Dawes Jr. reveals that the tuppence Michael deposited in the first film was invested and gathered enough interest to be able to save the Banks family home. In the process, Mr. Dawes Jr. strips Wilkins of his position as president of the bank and asks Hamilton and Frye to escort him away. This, in turn, shows that Mr. Dawes Jr.'s redemption since the first film is permanent.
He has a slight habit of dangling his locket watch from his right hand, something that his animated wolf counterpart picks up on.
- Colin Firth, who played Mr. Wilkins, also voiced the Wolf in the animated sequence of the film. This implies that the Wolf is Mr. Wilkins' animated representation (signifying how he is a metaphorical "wolf in sheep's clothing") and thus allows the Banks children to realize that Mr. Wilkins isn't what he seems to be.
- In spite of being the nephew of Mr. Dawes Jr. and thus the grand nephew of Mr. Dawes Sr., Mr. Wilkins is never mentioned to have the surname "Dawes" on his name.
- Furthermore, Wilkins' existence reveals that either Mr. Dawes Sr. had at least a daughter (who wasn't seen in either film), who in turn would be the sister of Mr. Dawes Jr, or that Mr. Dawes Jr. has a wife whom we’ve never met, and Wilkins is on his wife’s side of the family. If Wilkins was the son of Mr. Dawes Jr.’s brother, then he would probably have “Dawes” in his name.