Actor Harriet Walter, who plays Lady Caroline Collingwood in the hit comedy-drama series Succession, has been roped in as Margaret Thatcher in Channel 4 drama series Brian and Margaret, directed by Stephen Frears.

The series, written by James Graham, also stars Steve Coogan.

The two-part series dramatises the occasion of and the story behind Margaret Thatcher's last interview, which proved to be the last straw that broke the camel's back with regards to her prime ministership. The interview with her old friend Brian Walden (Coogan).

The series, based on two chapters from ex-BBC producer Rob Burley's Why is This Lying Bastard Lying to Me, is expected to "ask whether the slow death of full-length political TV interviews puts modern democracy at risk."

Brian and Margaret is the first project greenlit by Director of Film4 and Head of Channel 4 Drama Ollie Madden after she took the reins. The series, produced by Dan Winch, is executive produced by Sarah Montieth, Rupert Majendie, and Delythe Scudamore.