Complex sentence: In 1955, Gibb formed the skiffle group The Rattlesnakes, consisting of himself on vocals and guitar, Robin and Maurice on vocals and friends/neighbours Paul Frost and Kenny Horrocks also providing vocals.
Split into simpler sentences: In 1955, Gibb formed the skiffle group, The Rattlesnakes. Consisted of himself on vocals and guitar, Robin and Maurice on vocals and friends/neighbours Paul Frost and Kenny Horrocks also providing vocals.