Richard E Grant heading to Downton

Withnail and I star Richard E Grant is leading a trio of star actors heading to Downton Abbey for the fifth season of the hit show.

Actor Richard E Grant will join the cast of Downton Abbey for the hit drama's fifth season. (AAP)

Richard E Grant, Four Weddings and a Funeral star Anna Chancellor and Serbian actor Rade Sherbedgia have signed up to join the cast of Downton Abbey for the hit drama's upcoming fifth season.

Withnail and I star Grant will play a guest of Lord and Lady Grantham on the show, while Chancellor has been cast as Lady Anstruther. Sherbedgia will play a Russian refugee on the show.

Announcing the new cast members on Friday, executive producer Gareth Neame said: "The characters they play are set to bring yet more excitement and intrigue to the show."

* Downton Abbey season four will air soon in Australia on the Seven Network.