Sir Paul McCartney found singing 'The Christmas Song (Chestnuts Roasting On An Open Fire)' "intimidating" as so many great musicians have already covered it.

The legendary singer recorded the festive track for a special edition of his 'Kisses on the Bottom' album, 'Complete Kisses'.

Speaking to NME, McCartney explained: "Doing Chestnuts was a bit intimidating because when you do these old songs, there's so many good versions of them - particularly Nat King Cole's in this case.

"So, I thought, 'You know what, I'm not even going to listen to it, I'm not going to see who's done it, I'm not even going to figure out how I'm going to sing it'. So it was just done in one afternoon in New York. And I'm quite pleased with it, because it's not like anyone else's version."

McCartney's 'Complete Kisses' also includes a DVD of a concert filmed at Capitol Studios in Los Angeles earlier this year.

The show will air on ITV tomorrow (November 24).