If any single recording shows why The Beatles broke up, it is Maxwell's Silver Hammer. Compulsively fertile in melody and fascinated by music's formal beauties, McCartney could, when unrestrained by Lennon's cynicism, fatally neglect meaning and expression. This ghastly miscalculation - of which there are countless equivalents on his garrulous sequence solo albums - represents by far his worst lapse of taste under auspices of The Beatles.

The cheery tale of a homicidal maniac, it was written towards the end of recording for The Beatles in October 1968 and tried out then (and later during the 'Get Back' sessions in January which I've been able to get a bootleg version featuring John Lennon doing a very strange vocal.) According to Lennon, who despised the song, McCartney was convinced that, given the right production, it was a potential hit single, and so flogged it to death in the studio in a pedantic effort to perfect it.

As he had with Ob-La-Di, Ob-La-Da, he merely ended up driving his colleges mad. Thus Abbey Road embraces both extremes of McCartney: the clear-minded, sensitive caretaker of The Beatles in You Never Give Me Your Money and the Long Medley - and the immature egotist who frittered away the group's patience and solidarity on sniggering nonsense like this.