The cast of The Ballad of Wallis Island have revealed the songs in their lives that hold the most sentimental value.

"Mine's 'She's a Rainbow' by The Rolling Stones", shared Tim Key, who plays eccentric millionaire Charles Heath. "I've got a lot of connotations with that, I've used it in a lot of theme tunes. I sort of always go back to that track."

Key's co-star Tom Basden meanwhile, shared his love for a Smiths classic.

"I think mine's probably 'I Know it's over', it got me through sixth form," the actor said. "I relied heavily on that song."

The Ballad of Wallis Island is very much about the nostalgic power of music, detailing the old tensions between former bandmates and lovers that resurface during  a private show at Charles' island home. The feature's original soundrack was written by Basden, who plays Herb McGwyer, one half of the songwriting duo McGwyer/Mortimer.

"I've been writing songs for myself at home over the years, never thinking that I'd do much with them," he said. "This was the ideal way for me to use those songs, to do it through a character, so it's not quite as exposing or embarrassing as it would be if I did it myself."

"What I think Tom managed to do, which is the secret sauce of the film, is tell the characters backstory through the story through the music, and allows the characters to talk to each other through the music. Tom tells that story really beautifully."

"When he first did it, which was 18 years ago," added Key. "It was one of the highlights of doing it. Hearing him play them for the first time was fantastic."

• The Ballad of Wallis Island is in cinemas 30 May