EXCLUSIVE: Howards End star Joseph Quinn is in advanced talks to join Helen Mirren and Jason Clarke in the cast of HBO and Sky’s upcoming mini-series Catherine The Great.

Quinn will play the role of Catherine’s son and heir, Prince Paul.

Oscar-winner Mirren will star as the iconic 18th Century Russian monarch who ruled for 30 years. Written by Nigel Williams (Elizabeth) and directed by Philip Martin (The Crown), the four-parter looks at Catherine at the end of her reign and her affair with Grigory Potemkin, who will be played by Zero Dark Thirty star Jason Clarke. Mirren and Clarke are the only cast reported before today.

Produced by Origin Pictures and New Pictures, the show will air on HBO in the U.S. and Sky Atlantic in the U.K. and Europe. The drama will be Mirren’s first major TV role for more than a decade. Filming is due to start in the fall.

Rising actor Quinn, who played Leonard Bast in Kenneth Lonergan’s BAFTA-nominated BBC/Starz drama Howards End, will next be seen as Enjorlas in BBC/Masterpiece series Les Miserables, with Dominic West, Lily Collins and David Oyelowo, and he stars opposite Molly Windsor in upcoming UK feature Make Up, which is in post. He is repped by Curtis Brown. HBO and Sky declined to comment.