Sir Paul McCartney to marry Nancy Shevell

Sir Paul McCartney is to marry his girlfriend of four years, New York businesswoman Nancy Shevell.

The former Beatle, who is 68, has become engaged to 51-year-old, who will become his third wife.

Sir Paul's first wife, Linda, died of cancer in 1998. He married Heather Mills in 2002 and divorced in 2008.