The Famous Five

 The Famous Five  was a series of mystery books written by Enid Blyton. According to the Tenth Doctor, The Troubleseekers books were rip-offs of this series and The Secret Seven. (PROSE: The Mystery of the Haunted Cottage)

In an alternate timeline created by Lenny Kruger in which the Common Men rose to prominence in place of the Beatles, John Lennon was a member of a group called the Famous Five, which was a joke name because there were only four of them: him, two Petes and Chaz. (AUDIO: 1963: Fanfare for the Common Men)