A new Lennon and McCartney collaboration is the last thing anybody expected. Yet fans of the Beatles have been taken by surprise by a new single released by the sons of two of the Fab Four - James McCartney and Sean Ono Lennon, who are both musicians themselves. The new single, entitled “Primrose Hill” after a park in north London that offers a panoramic view of the city, was announced by McCartney, son of Paul and his late wife Linda, on Instagram four days ago.