Airing later this month, the one-off drama explores Isherwood’s formative years in 1930s Berlin in the run-up to the Second World War and co-stars Lindsay Duncan (Doctor Who: ‘The Waters Of Mars’), Imogen Poots (28 Weeks Later), Toby Jones (Doctor Who: ‘Amy’s Choice’) and Douglas Booth (Worried About The Boy).

Smith told BBC Press Office: “This has given me a great respect for people like Michael Sheen. But I hope I’ve captured a moment – that little glimpse of glee in Christopher’s eye you know he had; that mischief.”

He added: “Just thinking in a different way physically to The Doctor was also a very interesting challenge for me because one is based on movement and madness and the other on stillness and stiffness really. I hope that you look at this and quickly forget that you’re watching The Doctor.”

Asked whether he would consider playing another real person on screen, Smith revealed: “Well I’d quite like to play Ted Hughes. That would be cool.”

Born in 1930, Ted Hughes was British Poet Laureate from 1984 until his death in 1998. He was married to American poet Sylvia Plath from 1956 until her suicide in 1963. Hughes was portrayed by Daniel Craig in the 2003 film Sylvia, alongside Gwyneth Paltrow as Plath.