Johnson was born in Truro, Cornwall, on 24 December 1874. Her father was James Tregay, a miner, who was blinded as a young man and ended up becoming a basket weaver. He believed in Irish home rule. Johnson was educated in Whitelands College in Chelsea, London, qualifying in 1894 as a teacher. She went to work in St. Multose's National school, Kinsale. There she met Thomas Johnson. She married him in Liverpool in 1898. He had worked in Kinsale where he met Johnson but went on to take a job that moved him with his family to Belfast. They had one son, actor Thomas James Frederick Johnson, in 1899. Both of them became involved in trade unionism. Her husband went on to become the leader of the Irish Labour Party, a TD and a Senator.[1]