WHAT HAPPENED when Sigmund Freud met Salvador Dali? Not much, in reality. The prominent thinkers enjoyed a cup of tea at Freud’s Hampstead house on a July afternoon in 1938.

There were a number of factors that limited communication; Dali couldn’t speak German or English, although that didn’t stop the two men “devouring each other with our eyes”, as the surrealist artist would later write. Psychoanalyst Freud was 82 at the time, dying from the jaw cancer that had blighted his life for the previous 16 years.

According to Michael Cabot, director of London Classic Theatre’s new version of Hysteria – Terry Johnson’s play based around the real-life encounter – Freud was “not in the physical or mental place to meet Dali full on. He was very poorly at the time and there was a sense that he was coming to the end – that he wasn’t quite as intellectually robust as he might have been.”

The lack of fully-fleshed recorded detail about the meeting meant that Johnson, whose play premiered in London in 1993, filled in the gaps with his imagination, borrowing from the absurdist artistic process of Dali and the “morphine-warped” inner workings of Freud.

The production is technically classed as a farce, and indeed all manner of bizarre events occur as the plot unfolds but there is a traumatic historic context underpinning the action. Hysteria is set the day after Kristallnacht, the Nazi-organised night of violence against Jews across Germany. Freud had earlier fled his occupied homeland of Austria but not before making quips about the Nazis’ aggressive anti-intellectual campaign. “What progress we are making,” he said. “In the Middle Ages they would have burned me. Now, they are content with burning my books.”

Cabot says: “There is a deep, serious and very real background running through the piece – the audience are made very aware of where they are. The research is impeccable – Terry Johnson is very much master of his material.” Merging slapstick comedy with the dark underlying tone of the play seems a delicate business.

Cabot agrees. “I spoke to Terry Johnson about this, asking him how he tied the two elements together. You have to feel them both in the air at the same time and trust that they can happily co-exist. It’s a brave playwright decision – it feels like two plays in one, almost. There are deep and dark waters but also a madcap farce that comes out of nowhere with Dali’s arrival.”

Like any director, Cabot is always on the look out for audience reaction. His keenness to gauge the atmosphere every night is accentuated by the dual aspects of the production.

“What I get from watching the audience is that they find it really disconcerting. The production never lets you sit back and relax – it pulls you from pillar to post. The farcical elements need to be very quickfire, but you need to give the more serious parts room to breathe.”

While Freud and Dali are the names that draw audiences to the play, its central character is a relative unknown, Jessica, a woman with her own traumatic past who finds her way to Freud’s house. After knocking on the window, she is let in and from there the plot spirals into disorder.

Fittingly for a story about two men concerned with the extremities of the human psyche – Dali for art, Freud for science – Hysteria skilfully weaves mind-warping psychedelic elements into the narrative. “Some of what we’re seeing may be imagined,” says Cabot. “It’s possibly a dream and possibly hallucination. All kinds of crazy things start to happen.”