The Beatles were not the beginning of Liverpool music but they are an almost inescapable starting point. In fame and influence the group stands at the zenith of our narrative arc: in them we can trace everything that went before, and their imprint is seen on everything after.

Through the Beatles’ writing we see a city's whole history distilled, its musical traditions alchemized. Never before, and seldom since, was an act so closely identified with its place of origin. In 1963 the Beatles’ accent and presumed attitudes fed a universal conception of Liverpool as young, fresh, cheeky and optimistic. If the impression proved short-lived, there was at least an authentic connection between the group and its home city. This is not to stuff the butterfly back into its chrysalis – the Beatles were undeniably original, and developed in ways that nobody could have predicted. But our initial proviso remains: the Beatles were inheritors of Liverpool's musical tradition rather than its inventors.

John Lennon and Paul McCartney became songwriters because, in the feverish activity of Liverpool's beat scene, there was a shortage of American rock and soul songs for each group to cover. Few of their rivals aspired to be writers: in that time of Tin Pan Alley it was considered a specialist craft. (Ironically, the first Liverpool rock star Billy Fury, the Beatles’ immediate predecessor, was a rare exception: he penned several songs, some under a self-effacing nom-de-plume, Wilbur Wilberforce. Sadly, none were deemed commercial, and all were consigned to the obscurity of LP ‘fillers’.) When a stable of ‘Merseybeat’ acts emerged in 1963 around the Beatles’ manager Brian Epstein, they usually sought material from the standard American sources or else from Lennon and McCartney themselves.

For all the flair of their composing, little in the first four years of John and Paul's partnership was lyrically distinctive. Stern conventions still applied to popular songs for the young: it is amusing to contrast the orgasmic patterns of ‘I Want to Hold Your Hand’ – tension, crescendo and release – with its chaste physical agenda. A new dispensation swiftly followed: Lennon in particular was straining at the lyrical leash. Emboldened by success, the mid-period Beatles looked outwards for ideas – to Bob Dylan, to Indian raga, to chamber music. And yet, as we will see, they were simultaneously delving backward. To Liverpool.