One of the best and most commercially successful pop/rock acts of the British Invasion, when the Hollies began recording in 1963, they relied heavily upon the R&B/early rock & roll covers that provided the staple diet for countless British bands of the time. They quickly developed a more distinctive style of three-part harmonies (heavily influenced by the Everly Brothers), ringing guitars, and hook-happy material, penned by both outside writers (especially Graham Gouldman) and themselves, eventually composing most of their repertoire on their own.