Joining the previously announced Mark Gatiss in the production will be Adrian Scarborough (Don Juan in Soho, Gavin and Stacey), who will play Doctor Willis. The piece follows the manic monarch (Gatiss), who slowly becomes mentally ill in the late 18th century. It won a string of awards when it first debuted in 1991, as did the 1994 film adaptation, both starring Nigel Hawthorne.
The Playhouse's artistic director Adam Penford will direct the production. He said: "Adrian and I have been looking for a project to work on together for a long time. He and Mark are two of the UK’s leading theatre actors; their combined talents on stage in this modern classic will be theatrical dynamite…the play is dramatic, moving and funny and focuses on power and identity, examining the fine line between a King and a man."
Scarborough and Gatiss will also both appear in Disney's upcoming film Christopher Robin.
The show has also announced it will extend its run by a further week in November, now ending on 24 November. Tickets for the extension go on sale on 13 April.
The Madness of George III runs from 6 November to 24 November with previews from 2 November.