Colin Firth shifted the pounds to play a prisoner of war in upcoming movie The Railway Man.

However, with filming having long ended, it looks like the slimline Colin Firth may be here to stay.

Colin Firth, 52, was looking trim as he attended his newest director Woody Allen’s jazz band performance on the French Riviera on Sunday.

The actor has been cast in Woody Allen’s latest film, which is yet to begin shooting, alongside Emma Stone, Marcia Gay Harden and Eileen Atkins.

Colin Firth has been cutting a slimmer figure in recent months after losing weight to play Eric Lomax, a real-life Scottish soldier who was subjected to torture by the Japanese during World War II in Burma.

Colin Firth shifted the pounds to play a prisoner of war in upcoming movie The Railway Man

Although filming finished quite some time ago, Colin Firth is yet to return to his usual size.

The actor may like his trimmer fame, or perhaps he is required the keep the weight off for another film.

This year, busy Colin Firth has several films in the pipeline, including Devil’s Knot, with Before I Go To Sleep, Genius and the Woody Allen project, which is as yet untitled.

The Railway Man sees Colin Firth play Eric, who was tortured by Japanese Kempeitai military police when he was sent to work on the Death Railway after being captured in Singapore in 1941.

Colin Firth plays the elder Eric, who is convinced by his wife Patti (Nicole Kidman) to find peace for his trauma by tracking down the Kempeitai interpreter, Nagase Takashi, who attended his interrogations and beatings years earlier.

War Horse star Jeremy Irvine plays the younger Eric and also had to lose weight for the role.

Jeremy Irvine admitted he walked to lose the weight in an interview with GQ magazine: “I’d walk all day through the Cambridgeshire countryside with my script to burn calories. I think I scared my mum a bit.”