In 1992, Mr Mason was the wealthy builder invited by Vernon Dursley to have a dinner party at his home along with his wife, because he was hoping to secure an investment from him in his drill company.
However, their dinner with the Dursleys was ruined and the deal was not secured following the unexpected arrival of Dobby, who destroyed Petunia Dursley's prized pudding in an attempt to prevent Harry Potter from going to Hogwarts that year. The dinner could have been potentially saved with some ice cream as a replacement desert, but Dobby's use of the Hover Charm in a Muggle home resulted in the Ministry of Magic sending Harry a letter via Owl, believing he had used magic in front of Muggles and warned him about doing so. Mrs Mason however also happened to suffer from ornithophobia, the mortal fear of birds, and the presence of the owl and the dropping of its letter on her head caused to her become terrified and she subsequently fled the house screaming about lunatics. Mr Mason stayed just long enough to explain his wife's mortal fear of birds and to ask if the evening had been the Dursleys' idea of a joke.
- Harry Potter and the Chamber of Secrets (First appearance)
- Harry Potter and the Chamber of Secrets (film)
- LEGO Harry Potter: Years 1-4