How do you write a hit song?

Available for over a year

John Seabrook, New Yorker staff writer and author of The Song Machine explains modern methods of songwriting, where you no longer need a room full of expensive musicians, and what makes a hit song. This clip is from the upcoming Music Likes series (part of the BBC Identity season) Image: Ed Sheeran, one of the most successful of the modern singer-songwriters Credit: BBC