Sir Paul McCartney has penned an emotional track inspired by his fear of opening up about his love for third wife NANCY SHEVELL.

The Beatles icon admits he struggled to tell the New York socialite his real feelings after they started dating, so poured out his heart on Scared, a song which appears on his upcoming album New.

He tells Britain's The Sun, "It can be quite hard to say 'I love you' to someone. I felt this with Nancy but to say it wasn't that easy.

"There are a couple of tracks about Nancy and Scared is one of them."

MCCartney has previously penned tracks for the major loves of his life, including And I Love Her for actress Jane Asher, My Love for his beloved first wife Linda, and Heather, the track inspired by his ill-fated marriage to Heather Mills.

The musician and Shevell wed in 2011.