Wicked Little Letters director Thea Sharrock sometimes struggled to keep it together while shooting the comedy.

In the new British film, Olivia Colman’s Edith Swan receives rude, indecent letters in the post and accuses her rowdy, potty-mouthed neighbour Rose Gooding, played by Jessie Buckley, of being the culprit.

In an interview with Cover Media, Sharrock revealed that she and the crew found it harder to hold back their laughter than the actors in front of the camera.

“It wasn’t them (the actors) that was ever in trouble, it was the other people either in the scene or on set,” she explained. “We had to really struggle sometimes to (keep it together). I had to completely look away often and hold my nose because my shoulders were shaking… I had to sort of hide myself in corners sometimes during the filming.”

The Me Before You director made the admission when she and screenwriter Jonny Sweet were asked which actor was the worst for breaking character while reading out the vulgar insults.

“They were all so disciplined in that regard,” Sweet replied, to which Sharrock added, “If we’re gonna tell the truth, they were all brilliant and they were so well prepared.”

Wicked Little Letters is based on a real-life case that made headlines in the 1920s. While researching the film, Sharrock got a kick out of reading the real letters in the perpetrator’s handwriting.

“(The author) had the most exquisite handwriting so reading unbelievably rude text in this beautiful handwriting was something I enjoyed,” she joked.

Wicked Little Letters is released in U.K. and Irish cinemas on Friday 23 February.

© Cover Media