1919 photo from Seaman's card
Leave Book has him as JH Cooper. There are merchant marine certs for James Hedley Cooper b1888 (cert 1910) and John Henry Cooper b1892 (cert Oct 1918). James Hedley Cooper can be ruled out as he served with Indian Marines and RE in WW1, and had a rank. So looking at John Henry Cooper, and RIC gaives him as John Henry Cooper b 2 Jun 1892.
1892 Jun 2. Born Liverpool.
1901 census at 22 Etria St, Everton
1911 census at 15 Upper Baker St. Liverpool
1918 Oct 31. Gains 2nd Mates cert. His address was 45 Mansell Rd, Liverpool
He is sailing on commercial shipping in 1918 and up to end of 1919 from his seaman's card
1921 May 24 . Accepted in England. Joined ADRIC with service no 1996. Posted Q Coy
1922 Jan. Still serving at demobilisation of ADRIC
1939 Register Living with wife Elsie at 106 Score Lane , Liverpool. He is an Insurance Agent
1972 Jul/Sep Died Liverpool (correct dob)