[2] In 1935, Pamela Kellino met actor James Mason on the set of his second film, Troubled Waters, on which her husband was working as a cinematographer.

The Masons moved from London to Hollywood in the late 1940s, occupying the mansion previously owned by Buster Keaton, where Pamela became a popular hostess of parties.

[9] Pamela Mason continued to live in the Keaton mansion in Beverly Hills until her death,[10] sharing it "with a multitude of free-range cats.

Most notably, she co-starred with James Mason in the films The Upturned Glass and Charade (directed by Roy Kellino), both of which she also co-wrote.

The Masons co-produced the films I Met a Murderer and Lady Possessed, both of which were directed by Roy Kellino and lost money.

[10] From the late 1950s through the 1970s, she made occasional appearances as a guest star on various TV series, including Playhouse 90, Love, American Style, and Wonder Woman.

[5] In 1947, she made her American stage debut in the title role of the Broadway show Bathsheba, in which James Mason co-starred as "David"; it closed after only 29 performances.

In addition to her screenwriting work, Mason authored a number of books, both fiction and non-fiction, some of which were published under the name "Pamela Kellino".