The Walking Dead star Lennie James has said there needs to be much more of a "conversation" about the casting of roles.
Amid a growing clamour for actors to have lived experience of the characters they are playing, he called for debate especially "in areas where the authenticity has been underserved".
The Line of Duty actor is currently in rehearsals for A Number, a psychological thriller at the Old Vic theatre in London, opposite I May Destroy You's Paapa Essiedu.
James told the BBC: "Where gay actors have not been given the opportunity to play gay parts, or disabled actors have not even been considered for the opportunity to play disabled parts, in that situation then I would 100% be part of the conversation of saying, why not? That absolutely should change."
But he insisted he would "challenge" the idea that certain roles must be reserved for particular actors to ensure their performance is authentic.
The Save Me actor and writer said the casting of any role had to be "on a case by case basis. I don't believe in blanket statements... because then the role of the actor slightly changes and is slightly different to the one I hope and pray that it is".
His comments come after Dame Maureen Lipman questioned the casting of the non-Jewish actor Dame Helen Mirren as the former Israeli Prime Minister Golda Meir in an forthcoming film.
"The Jewishness of the character is so integral," Dame Maureen told The Jewish Chronicle.
Last year the Bafta-winning writer Russell T Davies, talking about his Channel 4 Aids drama It's a Sin, which only featured gay actors in gay roles, told the Radio Times: "You wouldn't cast someone able-bodied and put them in a wheelchair, you wouldn't black someone up. Authenticity is leading us to joyous places."
Marlee Matlin, the only deaf actor to win an Oscar for the 1986 drama Children of a Lesser God, has also spoken out on behalf of deaf actors.
"Enough is enough," she told The Guardian last year. "Deaf is not a costume. It's not authentic and insults the community that you're portraying. Because we exist, we deaf actors."
But other actors have called for a more nuanced approach, believing it is part of the actor's job to inhabit a totally different character.
The multi-award winning actress Cate Blanchett has said: "I will fight to the death for the right to suspend disbelief and play roles beyond my experience."
And speaking to Radio 4's World at One following her comments about Dame Helen's casting, Dame Maureen herself also acknowledged it was a "complex" argument.
"You simply would rule out the whole skill and craft of acting if you cast narrowly," she said, before adding: "I am not someone who believes Shrek should be green."
James, 56, admitted he was "scared witless" by his latest role in A Number, a play about the ethics of human cloning.
He is returning to the stage after a 16-year absence.
Appearing alongside him will be Essiedu, 31, who was the first black actor to play Hamlet for the Royal Shakespeare Company in 2016.
The pair have known each other since Essiedu was chosen as one of Bafta's Breakthrough Brits in 2018. Recipients are given mentors in the industry.
"They ask you, 'Who do you want to meet?' You can meet Steven Spielberg. I was like, 'I'll meet Lennie James,'" laughs Essiedu, who cites James as an early career inspiration.
With James based in Austin, Texas, filming Fear the Walking Dead, and Essiedu in London, the pair kept in touch online, via email and Zoom.
"The first time we actually met in person was on the first day of rehearsals (for A Number)," says Essiedu.
Unfortunately, the experience was "profoundly underwhelming" thanks to Covid, he explains.
"I think we bumped fists or even elbows."
In A Number, James plays a father, with Essiedu playing his three sons, two of whom are clones of the first.
Caryl Churchill wrote the play in 2002. The first production, at the Royal Court Theatre in London, starred Michael Gambon and Daniel Craig, well before he went on to play James Bond.
The Guardian's Lyn Gardner described it as an "engrossing spectacle", adding: "The success of a disturbing evening lies in Churchill's ability to raise big moral issues through the interstices of close human encounters."
But, she noted, "Although the play is in part an attack on patriarchy, it doesn't supply enough hard information to resolve the issue of whether character is determined by genetic or social factors."
In 1996, scientists had made history by creating Dolly the Sheep, the world's first mammal cloned from an adult cell.
Researchers hoped the scientific experiment would help to treat debilitating diseases, but critics were worried it opened the door to human cloning, designer babies and a dystopian future.
"The version we are doing is set in the here and now, where cloning is a possibility, a bit like it is now," explains James.
After Dolly's birth, countries across the globe began to adopt their own laws regarding human cloning. Although the UK allows the use of cloned human embryos for therapeutic purposes, it has banned reproductive cloning which would aim to create a new-born baby that is genetically identical to another human being.
"If they hadn't put the restrictions on the process that they put on when Dolly the Sheep was done, who knows what situation we would be in 20 years later?" asks James.
"And this play supposes a future on from that and that's where we've set it. So we're not going to be dressed in white space suits and be talking to the walls."
Essiedu adds: "It's not a sci-fi play about Paapa Essiedu trying to copy himself and Lennie James watching that. It's about personal relationships."
James says while cloning is the "springboard" for the play, A Number is primarily about "the relationship between fathers and sons."
His return to the UK stage also means an opportunity to catch up with old colleagues.
James, who played Gates, the embattled DCI Tony Gates from the first series of Line of Duty, says when he comes home, he and his former co-stars Adrian Dunbar, Martin Compson and Vicky McClure will "all go and grab a curry together."
He is also still in touch with the show's creator Jed Mercurio, too. The sixth series was billed as the final one, but could the show return?
"I think there's another season to come," says James. "But if I've just let out a secret, I'll own it."
A Number is at the Old Vic from 24 January until 19 March.