Lucy Prebble, the playwright behind The Effect, which premiered in London last night, has revealed that she wrote the play for her good friend Billie Piper and her “huge heart.” The play is inspired by the 2006 medical trials by Parexcel, during which six volunteers were taken ill with multiple organ failure. It’s Prebble’s first play since Enron, three years ago.

Prebble, 31, has described the play as a love story and explained to the Evening Standard that that required Billie Piper’s “emotional bravery.” The pair have been friends since they both worked on ITV’s Secret Diary of a Call Girl and Prebble spoke highly of Piper, saying “She’s a wonderful actor and one of the biggest hearted people I’ve ever known. I knew when I was writing the part I wanted someone who is an emotional resonator, able to give emotions and be likeable and charming. She is vulnerable, open - she has a huge heart.” In the play, two patients fall in love during a medical trial but are unsure whether it’s the drugs that have made them do so.

In order to undertake some research for the play, Prebble even volunteered to take part in a medical trial herself. “I was really scared,” she admits. “And I’m really squeamish. I find needles really difficult and it’s an incredibly intense environment. You’re in a hospital ward for weeks and weeks. I only did it for a few days.” The response to the play has been largely positive, with one audience member commenting “Billie Piper was stunning, absolutely stunning. It was beautifully done and well crafted.”