It also features seven original recordings by the cast. Elizabeth McGovern, who plays Lady Grantham, sings "It Came Upon a Midnight Clear" and duets with Julian Ovenden, who plays one of Mary Crawley's suitors Charles Blake, on "The First Noel."

"It was so exciting for me to have been given the opportunity to sing two songs in a totally different context to that which I'm accustomed: without my guitar, without my band," McGovern said in a press release about the albums, referencing her folk band, Sadie and the Hotheads.

Ovenden, in addition to being an actor, is a professional singer and musician. He performs additional tracks for the album, taking on "O Holy Night," "Silent Night" and "Sussex Carol."

"I'm a huge music fan and like Elizabeth I have a separate music career that runs alongside the acting," Ovenden said. "To do this album is therefore a massive honor and something I've really enjoyed doing."