Photo: Idris Elba and pregnant girlfriend step out at the Golden Globes in LA

British actor Idris Elba and his pregnant girlfriend Naiyana Garth joined forces on the red carpet at LA's Golden Globe Awards on Sunday.

The London-born screen star and his make-up artist partner - who have been dating since March - made a rare red carpet appearance for the annual ceremony.

Idris, who is the lead star in Mandela: Long Walk To Freedom, speaking previously about getting into character for movie he told the Daily Mail's Baz Bamigboye's he spent a night on Robben Island, locked in a cell next to the one where Mandela was jailed for 18 years.

He said: "I wanted the audience to know what it was like once Mandela and his colleagues were jailed and the crowds dissipated."

"It was a s***hole," Elba said. "I had a thin blanket for a mattress and that's all there was between me and the concrete floor. They gave me a bowl. I had no water, nothing to drink at all.

"I was wearing my sweats and what not. I had two iPads to document myself and a cell phone."