Sir Ian McKellen has joined forces with Swedish pop legends Abba for a comical festive video.

A video posted to the band’s Twitter page shows Bjorn Ulvaeus knitting on the sofa with the renowned British actor.

Surrounded by Christmas trees and decorations and dressed in woolly jumpers, they joke about “the early days” and the possibility of a fifth member.

“I’ve always thought Bjorn, that Abba might have really taken off if we’d stuck to the original idea, you know, of the five of us,” Sir Ian tells the singer.

Bjorn replies: “It could have but as you know it didn’t work out. But I appreciate this knitting we do every year.”

“Oh absolutely” says Sir Ian.

“It takes me right back to the early days when you wanted to do a lot of Shakespeare and I wanted to do a lot of singing.”

The video ends with the message “Merry Christmas from Abba and Ian McKellen.”