His music career began in 1959 when he joined Cass & The Cassanovas, a Liverpudlian beat group led by Brian Casser (rhythm guitar, lead vocals), with Adrian Barber (lead guitar, vocals) and Johnny ‘Hutch’ Hutchinson (drums). Throughout a five-year career they never recorded an album but released nine singles of little consequence except for a credible version of Morning Dew, and the psychedelic-ish I Can See Through You.The group struggled on for a few more months before Gustafson, along with Mick Underwood (drums) and J. Peter Robinson (keyboards), split to form Quatermass.