The secret behind Paul McCartney's secret track
16 October 2013 Last updated at 15:46 BST
Sir Paul McCartney has told how a secret track on his new album is about the difficulty he found in telling his now wife Nancy Shevell that he loved her.
He told John Wilson on Radio 4's Front Row how he realised he was too scared to say it - even though he could say the words in a song.
The track appears on Sir Paul's latest album New.
Front Row is on Radio 4 Monday to Friday 19:15.