Jasper Britton in Dan McCabe's The Purists at Kiln Theatre

Add in two young women, Val a street smart dealer with a burning ambition to be a rapper, and Nancy an actress who has co-opted hip hop for her feminist play, and the sidewalk becomes a forum for verbal wit and wizardry.

With its sharp, comic dialogue, Dan McCabe's The Purists airs generational and gender divides, race and politics - and how to keep an art form pure.

At its 2019 Boston premiere it was hailed a funny and thought provoking portrait of the power of music and friendship.

Richard Pepple as Mr Bugz and Sule Rimi as Lamont in The Purists at Kiln Theatre, Kilburn. (Image: Marc Brenner)

Now about to open at Kiln Theatre, it sees each man feeling their age; bisexual telesales agent Gerry recalls the friends he lost to AIDS, veteran DJ Mr Bugz frets about his mother's impending death, and rapper Lamont struggles to find a rhyme that will return him to the spotlight, while staying true to his roots.

Jasper Britton plays Gerry, a former millionaire who loves "show tunes and Broadway musicals and hates rap."

"He's a man with a permanent scowl who has been there done that, survived the AIDs crisis, travelled the world and given all his money away. He's not very woke and is a complete mess," he says.

"I get bored easily but when I read this it took my breath away - by the end of the first act I was absolutely gobsmacked.

Jasper Britton plays Gerry, a bisexual former millionaire who is 'messed up.' (Image: Supplied)

"It's an extraordinary beautiful and powerful play full of humanity, love with dramatic moments and issues that come up between friends.

"You see relationships between the three men develop in unexpected ways."

The two women, one a white and privileged from Scarsdale "the Hampstead of New York," the other a Puerto Rican drug dealer, get into a rap battle with the men judging who wins.

The Purists sees Mr Bugz and Lamont shake down hip hop's 50 year history unpacking everything from gangster rap and misogyny to mainstream appropriation.

Tiffany Gray plays Val Kano in Dan McCabe's The Purists. (Image: Marc Brenner)

As someone whose knowledge of rap extended to buying the Grandmaster Flash 12inch, Britton says: "It's been a bit of an education."

"These two have an opinion about everything, right from the word go they are arguing about who's the best rapper, it's a cultural debate about the history of rap but it's not a history lesson.

"They talk about artists past and present, how do you keep the art form pure, what it means when new people come in and how it stays true to its roots.

"Doing this has made me see how clever the people who do it are. To my elderly white man's eyes it is much closer to poetry and the expression of thoughts and feelings - it has real soul, which really surprised me."

While audiences may be "shocked, challenged, or uncomfortable" he adds: "This play is a sanctuary, it has some peace in it."

Britton's half sister is TV presenter Fern and his dad was Tony, veteran of 60s movies like The Day of the Jackal, and 80s sit coms like Don't Wait Up and Robin's Nest.

While his career has seen him take lead roles at the Old Vic, RSC, National Theatre, and West End, with screen stints in My Dad's The Prime Minister and last year's Apple TV thriller Hijack, he says he's no nepo baby.

"Dad meant well and did his best, but when I started out he was cruising at 37,000 feet and I was the flightless cabbage bouncing along the runway. I felt I couldn't remotely be a part of what he was doing and it wasn't really somewhere I saw myself.

"People often come up and say 'he was so proud of you' but I never knew. Most of the time I felt he looked down on what I did and I never played on his name."

Of sister Fern who braved the Big Brother house in March, he says: "She's so bloody good at what she does".

"I felt really terrified for her on Big Brother worrying is she going to be alright, because people go loo-lah in there. But she has such incredible reserves of strength and emotional resilience, she has needed it over the years, I am in awe of her."

The Purists runs from 14 November – 21 December at Kiln Theatre, Kilburn.