After shrouding it in secrecy for several months, Paul McCartney and Lady Gaga have shared a few details regarding their recently recorded duet.

Deadline reports that the song is one of "seven or eight" new McCartney recordings slated for inclusion in the soundtrack to High in the Clouds, a 3D animated movie based on his 2005 children's book of the same name. While the report doesn't name any of the songs, it describes the Gaga collaboration as "a rollicking tune" and adds that McCartney will voice one of the characters.

The High in the Clouds movie has been in the works for a couple of years, and has been described by McCartney as a "passion project" that he hopes will translate to "a warm, funny and moving animated film that will resonate with worldwide audiences."

The book, which McCartney wrote with children's author Philip Ardagh, was illustrated by Geoff Dunbar, whose work will be familiar to fans through his previous collaboration with McCartney on their 1984 animated effort Rupert and the Frog Song. The story, about a squirrel who searches for a legendary secret animal sanctuary after his home is overrun by human developers, was reportedly originally conceived as a film, so its journey to the big screen should prove particularly satisfying for McCartney.

ABC News Radio notes that this isn't Lady Gaga's first foray into classic rock-related animation — she also worked with Elton John on "Hello Hello," a song included in the soundtrack to his 2011 theatrical release Gnomeo & Juliet. The report includes quotes from a recent issue of Q in which McCartney admits Gaga initially hung up on his assistant when he called to ask if she'd like to be involved with High in the Clouds, so he had to call her back himself. "I'm conscious of people thinking it's a mate at work," he admits. "Saying 'Oh, f--- off, Fred! Stop doing your McCartney impression!'"

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