Staying with Transatlantic, his characteristically titled first album – Can I Have My Money Back? – began his real career in 1971, establishing him as a singer-songwriter, bringing folk fans with him and promoting his songs. It was Gerry who urged Connolly to go it alone as a comic. Despite US releases, singles written by Gerry (Shoeshine Boy and Saturday Round About Sunday) and John Peel sessions for the BBC, there was little reaction and tensions grew between these strong personalities. The Humblebums' first LP, on the folk-oriented label Transatlantic, predated Gerry's involvement, but he and Connolly were the group for the albums The New Humblebums (1969, with cover art by Byrne, a partnership that later spanned the albums of Gerry's heyday) and Open Up the Door (1970). Billy Connolly was also in Clydebank, and after Gerry's song Benjamin Day failed as a Mavericks single, Gerry and Egan quit the group and Gerry joined Connolly's outfit, the Humblebums, a Clydeside folk act. Byrne, also educated at St Mirin's, had long been Gerry's mentor, and had first interested Gerry in playing the guitar. They married in 1970, after courting at the bohemian bungalow of the artist and future playwright John "Patrick" Byrne and his wife, Alice.
She was 15, from an Italian Clydebank family. At a dancehall in 1965, Gerry met his future wife, apprentice hairdresser Carla Ventilla. At weekends, he and a schoolfriend, Joe Egan, played in a local group, the Mavericks. That year, Gerry left St Mirin's academy and worked in a butcher's shop and at the tax office.