Stephen Frears and Hugh Grant on film Florence Foster Jenkins and working with Meryl Streep

Hugh Grant and director Stephen Frears talk about their new film Florence Foster Jenkins, which stars Meryl Streep as the notoriously bad real-life 20th-century New York opera singer.

A comforting arm: Meryl Streep as Florence Foster Jenkins and Hugh Grant as St Clair Bayfield in what is the award-winning film, Florence Foster Jenkins. Pictures Mick Wall

Florence Foster Jenkins was a real-life American socialite who billed herself as being a great opera star – but is seemingly the only person who does not realise she is a horrible singer.

Nonetheless, she never let small details like the lack of tone and having no descernable musical talent stop her from performing, and became a prominent cult figure in the New York musical scene of the 1920s, ’30s and ’40s.

Now her unlikely celebrity is revived in an award-winning film about her life, starring Meryl Streep and Hugh Grant. Both have been nominated for best actress and actor Golden Globes at Sunday's ceremony, along with The Big Bang Theory's Simon Helberg, who has a supporting-actor nod, while the film is up for best musical or comedy film.

The stars have already been rewarded, with Streep picking up a Critics’ Choice Award last month, and Grant an Evening Standard Film Award and Hollywood Film Award.

British director Stephen Frears (High Fidelity, The Queen) did not know much about the singer when Nicholas Martin's script landed on his desk.

"I knew that [British actress] Maureen Lipman played her," he says, referring to the play Glorious, which was staged at the Duchess Theatre in London in 2005. His education about the real-life singer, therefore, came from watching YouTube clips of her performances.

“I thought she was fantastic,” says Frears.

When Streep was suggested for the title role, he was excited by the prospect.

“I thought she would be good and be something refreshing for her,” he says.

But perhaps the real casting masterstroke came in the decision to get Grant to portray Jenkins’s confidant, partner and manager, St Clair Bayfield. The British actor is best known for playing bumbling romantic leads, but Frears thought he was wasting his talent in lightweight romantic comedies.

“I’ve always thought he was clever,” says the director. “I don’t know why he makes the films that he makes.”

The sentiment is, surprisingly, echoed by Grant.

“When I flick on the television and see myself in a film I never think, ‘Oh he’s a great actor,’” he says.

“It’s like in the old days, when you would hear your own voice on an answer machine and it would make you feel nauseous. Well seeing myself on television is like that, times 50.”

This is a typically self-deprecating statement from the 56-year-old, actor who adds: “I’m too old to be starring in romantic comedies.”

This might explain why we have not seen much of Grant on screen recently, although he says it is not only a case of offers drying up.

“It’s true that I haven’t been doing much show business in the past few years,” he says. “I got involved in other things: I got involved in politics [he was a major campaigner for Hacked Off, which campaigned to change Britain’s press laws] and I got involved in having a baby – and then suddenly out of the blue, a script comes along that was well-written, funny and sad, which is rather unusual.

“It was directed by a classy director, Stephen Frears, and starred Meryl Streep – so that was easy to say yes to.”

Bayfield is the man who shields Jenkins from bad press, flatters her and arranges her concerts in such a way as to keep out any critics or journalists who might write a bad review.

“He appears on the surface to be this suave debonair Englishmen, very much in control,” says Grant.

“In reality, he was a failed actor and was always desperately scratching around for work, and the only thing that gave him a position in life was his relationship to this millionairess, Florence Foster Jenkins.

“What I enjoyed playing was that while his outer shell is of a debonair Englishman, inside he is a rather desperate man clinging to life because he has nothing else.”

Grant tells how Frears was faced with the choice of portraying two alternative interpretations of the life of Jenkins, and decided on the more comedic version.

“There are people who have looked into the history of her and say that she was on these heavy drugs for an illness that she had which made her mentally unstable and this is why she went on singing when she was clearly horrible,” says Grant.

“But we have gone for a more generous and uplifting interpretation, which is that she is one of those people who just loves what she does so much, there is so much passion, that she does it anyway.”

• Florence Foster Jenkins is in cinemas from Thursday, January 5.