Jamie Foxx has described his latest film, about an innocent man living on death row, as the “most important” he has ever done.

The US actor, 52, plays African-American Alabama native Walter McMillian, who was wrongly convicted of murder and sentenced to death in the late 1980s.

Speaking at a special screening in London, he said the nerves of playing such an important real-life role helped both him and his co-star Michael B Jordan rise to the occasion.

Just Mercy UK Special Screening – London
Co-stars Michael B Jordan and Jamie Foxx (Ian West/PA)

Black Panther star Jordan plays civil rights lawyer Bryan Stevenson, who was instrumental in Mr McMillian’s fight for justice.

Foxx told the PA news agency: “I’m from Texas so I am from the South. But talking with Bryan, talking with Michael about Walter, telling me who Walter was.

“Even though he was in this terrible situation, he was gregarious. He was hopeful and he would share that with his other inmates.

“We started working it out and crafting it and the next thing you know, you bring the butterflies and the angst, and all those things, on to the set.

“I think it worked because Walter himself was nervous that his life would be extinguished.

“They go on this journey and as you watch this movie, myself and Mike (are) both two balls of nerves and then we finally find our stride as the characters…

“It’s always great to put on the skin of a new character and find these great things and have people respond to it in a way that is like, ‘We didn’t see you or Mike – we saw both of you guys disappear’.

“It was, I would say, the most important movie I have ever done.”

Just Mercy is in cinemas on January 17.