He is notable for playing
Freddie Threepwood in
Blandings (2013–2014) and villain George Warleggan in the
BBC One drama series
Poldark (2015–2019). He has also appeared as George Balfour in
The Riot Club (2014), Marc Fisher in the
Netflix romantic comedy
Love Wedding Repeat (2020), Joe in
Maggie Gyllenhaal's
The Lost Daughter and as
Charles, Prince of Wales in the 2021 dramatic film
Spencer. For his work as Selby in
HBO/
BBC Rain Dogs (2023) he was nominated for an
Independent Spirit Award for
Best Supporting Performance in a New Scripted Series. In 2025, Farthing acted alongside
Angelica Huston,
Clarke Peters, and
Matthew Rhys in the BBC three-part television series
Towards Zero, an adaptation of
Agatha Christie's novel of the same name, playing the estranged nephew of Huston's matriarch. ==Personal life==