S.O Davies was the son of Thomas Davies, an active socialist in the late 19th and early 20th century. In the 1870s, Davies wrote scathing articles in the Welsh language newspaper Tarian y Gweithiwr denouncing bad management practices and poor safety records in the pits of the Rhondda and the Cynon Valley.

Davies later became an insurance agent. With that new role, Thomas enjoyed a position of influence and so during the 1898 miners' strike, which led to the formation of the South Wales Miners' Federation (SWMF), he took on the role of chairman of the Cap Coch soup kitchen. Davies and his sons were founder members of the SWMF and through it began to engage directly with politics. This 1906 petition from the SWMF is held in the Parliamentary Archives' collections.