Tony Award winner Nicholas Hytner (Carousel, The History Boys) will direct the film adaptation of the memoir by Tony winner Alan Bennett (The History Boys, Beyond the Fringe), which is based on the playwright's experiences with Miss Shepherd, a vagrant who parked her old van in his driveway and stayed for 15 years.

Smith also starred in the London stage premiere of Bennett's Van. She will be joined on screen by Alex Jennings (A Midsummer Night's Dream, "The Queen"), who will play the role of Bennett.

Her involvement in the film version was "essential," TriStar Productions' Tim Rothman told Deadline.com. "She is the lady in the van. I honestly don’t think that Alan or Nick would have wanted to do it without her."

Damian Jones ("Belle," "The Iron Lady") and Kevin Loader ("Venus," "In The Loop") will produce, along with Hytner. Miles Ketley and Charles Moore will serve as executive producers.

The film is aiming for a worldwide release in late 2015. Tony winner Smith's Broadway credits include New Faces of 1956, Private Lives, Night and Day and Lettice and Lovage. The two-time Oscar winner's film work includes "California Suite," "The Prime of Miss Jean Brodie" and "A Room with a View." She currently stars in "Downton Abbey." Her work at the Royal National Theatre includes Othello, Hedda Gabler, The Master Builder and Much Ado About Nothing. Smith has been nominated for six Olivier Awards.