Edward Fox appeared in Il servo di scena (1983). In the earlier version, Fox played Oxenby, while in this movie, Fox played Thornton.
Sir Anthony Hopkins was the principal champion for the project.
Ian McKellen said he re-recorded his lines for the American release because Americans couldn't understand his native northern accent.
Although "Sir" is based on Sir Donald Wolfit, the action has been transplanted back in time to World War II, a time when the real Wolfit, far from being an elderly actor, poor in health and prone to lapses in memory, was only about forty and at the height of his powers.
Three years after this film, Emily Watson and Anthony Hopkins appeared in Richard Eyre's King Lear (2018) film adaptation. Hopkins played King Lear and Watson played Regan (the second daughter of King Lear).