Now Am I Dead: The Truth Behind The Paul McCartney Is Dead Theory.

Do You Want To Know A Secret: The Theory After The Beatles

There are still clues left by the remaining Beatles and their wives. This could a running joke that is being played on Beatle fans since The Beatles did find the legend funny and left clues in their music and albums as a result to stir it up a bit with examples like them calling Paul, 'Faul' (the name given to Campbell directly meaning: Fake Paul), hoping that no one will notice. 

Or going as far as 'Faul' carefully admitting to the theory when talking about the phenomenon on talk shows, When filming interviews for The concert for George premiere, 'Faul' stops the interview to say hello to Olivia and Dhani Harrison (wife and son of George Harrison) in which Olivia welcomes 'Faul' by saying 'Hello Billy'. It is unknown if Olivia was talking to 'Faul' or not, but either way it was caught on camera.

 Also, the theory can explain why 'Faul' infamously said, "It's drag" about John Lennon's death in 1980. John and Paul were the best of friends and are considered the best song writing duo ever as they grew up together and shared similar experiences. 

On the other hand John and 'Faul' were the complete opposite, which is not surprising as John had lost his best friend and he had what can be described as a fear that men would leave him as it did with his dad Alfred and his much-loved Uncle George, so young John built up this idea that the men in his life would always leave him eventually. Another point to do with relationships is that Paul met his girlfriend Jane Asher in 1963, so Billy Shears would have had to fall in love with Asher or act like it. Which makes sense because they cut of their engagement in 1968 because of this instead of Paul cheating on Jane as being the lead up.