From the obituary here in the UK Guardian:
“Just a plumber from Edinburgh who got lucky” was Alan Longmuir’s dry assessment of his career. ... In their peak year, 1975, they had two UK No 1 singles, including the signature hit Bye Bye Baby; the end of that year saw them top the American chart with the stomping Saturday Night . . .. Alan and his younger brother, Derek – the Rollers’ future drummer – went to Tynecastle high school, which Alan left at 15. After a year of office work he was apprenticed as a plumber, but the job was secondary to his yearning to be a musician. ... He returned to working as a plumber and from 2000 until retirement was a bylaws inspector. ... He viewed the 70s with wry humour, saying in 2008: “I remember sitting at the bar of the Beverly Hills hotel – there was Patrick Magee, Barbra Streisand, David Soul – and Alan Longmuir, the plumber from Edinburgh.”