Thomas's first competitive game was at the age of 11 in September 1966, having been inspired by the World Cup success of that year, for BOCM Ladies as a traditional right winger. She was also encouraged by watching her father Percy, who had been a keen amateur footballer and a founder member of a local team called Air Street United. Her talents were quickly recognised and she was snapped up by Reckitts Ladies, then under the tutelage of Flo Bilton. A move to local rivals Hull Brewery Ladies followed, gaining recognition with the Hull and District Representative team, the North of England squad and an eventual England call up.