| Last updated
Meanwhile, Pennyworth star Emma Corrin is depicting Princess Diana during her turbulent marriage to Prince Charles.
Teasing the two new roles on Tuesday (29th September), Netflix UK and Ireland wrote: "It's time.
They shared two images with the post, one of Gillian as Thatcher outside Number 10 Downing Street as she was elected into office, and one of Emma as Princess Di being hounded by paparazzi.
The fourth season is coming out on November 15th, and will once again include Tobias Menzies as Prince Philip and Helena Bonham Carter as Princess Margaret. Olivia Colman also appears once again as The Queen.
It picks up in the late 1970s and will depict much of Prince Charles and Princess Diana's romance, as well as tensions between Margaret Thatcher and The Queen.
As Netflix explain: "Charles' romance with a young Lady Diana Spencer (Emma Corrin) provides a much-needed fairytale to unite the British people, behind closed doors, the Royal family is becoming increasingly divided."
As for The Queen and Maggie? Well, their relationship "only grows worse as Thatcher leads the country into the Falklands War, generating conflict within the Commonwealth."
The cast will all be appearing in their roles for the last time this season because passing the baton to a new set of royals for season 5, including Imelda Staunton who will take on the role of the Queen, Lesley Manville as Princess Margaret and Elizabeth Debicki as Princess Diana.
The Show will run for six seasons in total.
We can't wait to see the next instalment!
Chosen for YouChosen for You
Most Read StoriesMost Read