Greg Hassall and Charles Purcell do battle over the fab four. FOR OK, Ob-la-di Ob-la-da is the most annoying song ever written. And you won't find Revolution No 9 on too many iPods. But how many bands' dud tracks can you count on one hand? The Beatles deserve their place in the pop pantheon. They revolutionised the way pop music was written, recorded and talked about. They were funny, charismatic, hungry to learn and unafraid of controversy. They matured spectacularly over seven tumultuous years, then quit on a high note with the peerless Abbey Road. They were a genuine band,...