It could have gone down as one of the greatest lost plays of recent history.

In 1935, Sir John Gielgud, one of post-war Britain’s leading theatrical talents, collaborated with Terence Rattigan on an adaptation of the great Dickens novel, A Tale of Two Cities.

The play, which was to star Gielgud in the roles of Sydney Carton and Marquis St Evrémonde, was set to run until the actor received a letter from a company staging their own version of the novel which persuaded him to pull the plug at the last moment.

Now, nearly 80 years after its conception, Gielgud and Rattigan’s A Tale of Two Cities is premiering at the King’s Head Theatre under the direction of Adam Spreadbury-Maher.

At the heart of the latter’s vision, playing the characters originally meant for Gielgud himself, is a 24-year-old debut actor more renowned for his former stint as a drag queen.

“There is a kind of pressure, but it’s a very exciting pressure,” says Stewart ­Agnew when asked if Gielgud and Rattigan’s ­vision of the French Revolution set-drama can be justifiably revived.

“The language of Rattigan is beautiful – the characters come alive just from the text and Dicken’s story has obviously survived for years and years.”

After working the Edinburgh club circuit as a drag queen in his early twenties, Agnew, who hails from Dunfermline, moved south to study at the East 15 drama school in Essex.

It was there he met Spreadbury-Maher, the ­renowned artistic director of the King’s Head Theatre, who had stumbled across a faint reference to the lost play when researching Gielgud’s career.

They reviewed the script for a production at East 15, and now, having graduated from the school, Agnew is linking up again with Spreadbury-Maher for his professional performance debut. “Adam’s great,” says ­Agnew.

“I love his process – he’s very much about letting ­actors find their own way and explore their characters.”

That is just as well, such is the expectation placed upon each cast member.

Quality

Much like Gielgud’s original vision, eight actors are bringing 30 characters to life, with little to no set ­design or props distracting from their performance.

While Agnew was given the role of the Marquis St Evrémonde – “played in a typically decadent Victorian manner” – it is the lead character of Sydney Carton who he has particularly ­enjoyed getting to grips with.

“When I was given Sydney, I drew out a list of how I am similar to him and how I am different. The problem was that as this totally drunken, broken character, he has a lot of difficult ­imagery that you have to create sympathy for.

“As an actor, you have to give in to that imagery completely.

“I fell for him and started to see where he was coming from, so it’s been very ­rewarding to go on this journey with him throughout the piece.”

After so long in the making, that journey is finally coming to an end at the King’s Head this autumn.

A Tale of Two Cities is now showing at the King’s Head Theatre until October 19. For tickets, see www.kingshead theatre.com.