Michael Elwyn, Nathaniel Parker and Rufus Wright are set to star in The Audience by Peter Morgan next year.
Elwyn will play Anthony Eden, while Parker has been cast as Gordon Brown alongside Wright in the role of David Cameron.
They join the already announced Helen Mirren as the Queen and Haydn Gwynne in the role of Margaret Thatcher. Robert Hardy will play Winston Churchill and Paul Ritter will appear as John Major.
Final casting will be announced shortly.
Directed by Stephen Daldry, the production will run at the Gielgud Theatre from February 15 and is booking to June 15, 2013. Press night is on March 5, 2013.
Design is by Bob Crowley, lighting by Rick Fisher, sound by Paul Arditti and video by Ian William Galloway.
The Audience is produced in the West End by Matthew Byam Shaw for Playful Productions, Robert Fox and Andy Harries.