Marriage certificate obtained, showing Patrick as a coalminer, father Michael. So that rules out the policeman in Lancashire in the 1911 census. Further checking of the 1911 census in Normanton shows a John Digman at the same address as was given for Patrick on the marriage cert, and Fiona from the Dignan One Name Study (Guild of One Name Studies) has come up with a possibility in Roscommon in Ireland. So I think I have probably got about as far as I can with that at the moment.