Have you viewed the marriage certificate at
www.scotlandspeople.gov.uk? Who were his parents and how old did he say he was?
James Edward Curran, son of James Curran, sailor, Strangford, and Mary McDonald, was born on 2 June 1896 at Strangford, registered in Downpatrick. You can view a copy of the certificate at
https://www.irishgenealogy.ie/en/ but you'll need to check the marriage to be sure that he's the right person.
James Edward Curran, age 4, born Co Down, is in the 1901 census in Killyleagh, Co Down, described as adopted son of James Caffrey.