On Monday, July 6, 1964, Shaftesbury Avenue in London's West End was a scene of pandemonium the likes of which London hadn't witnessed since the day the Second World War ended. On this hot summer night, an invasion that had been percolating in the north of England for years finally came to a full boil. The Beatles' debut film was having its world premiere at the London Pavilion, replacing Tom Jones, the film that heralded the critical and even more importantly commercial arrival of the new British cinema explosion.
The Beatles — John Lennon, Paul McCartney, George Harrison and Ringo Starr — had burst onto the international pop music scene. Only a few short years ago, they were scruffy young lads from Liverpool, the industrial port city of the north of England, in love with rock 'n' roll, with faint dreams of stardom. The current lineup began with John Lennon asking Paul McCartney to join his group the Quarrymen, McCartney bringing in Harrison, with Lennon's art-school friend Stuart Sutcliffe joining and Pete Best settling in as their drummer, after many held that position in the group. Sutcliffe eventually dropped out to stay in Hamburg and pursue a career in art. When the group finally signed to Parlophone Records, Best was sacked, and Starr took his place.
Source: ultimateclassicrock.com