Two long-lost Peter Sellers films co-written by famed Canadian author and social critic Mordecai Richler will be screened at a U.K. film festival decades after they were created.

Dearth of a Salesman and Insomnia Is Good for You were both made in 1957, before Sellers became a global movie star with breakout roles in I'm All Right Jack and as Inspector Jacques Clouseau in The Pink Panther. 

Richler, meanwhile, was a 26-year-old and living in London when he wrote the films. The Montreal-born writer’s best known works include The Apprenticeship of Duddy Kravitz and Barney's Version.

The films were discovered in 1996 in a container outside a production company's headquarters by the building manager, Robert Farrow.

"I've had those films all this time, mostly in my cupboard at home under the stairs," Farrow told CTV News.

It wasn't until last year that festival organizers showed interest in the films.

Decades after they were created, the black-and-white films, which are about 30-minutes long, will have their first public screening during the opening gala of the Southend-on-Sea Film Festival in May.

But how Sellers and Richler came to work on the short films together remains a mystery.

"The trouble is all the people are virtually dead now who can tell us any stories," said Stephen Podgorney of Dimwittie Films. "We don't know how it began, we don't know why it ended."

With a report from CTV's Daniele Hamamdjian