Have you also considered the John Sullivan birth in County Antrim, with father John, in 1917 on UHF site?
Where did you get his birth year of 1919 from? Was it a handwritten entry in a bible/letter or such? If yes, could '7' have been read as '9'?
Hi scotmum, thanks for suggestion, yes I looked at this John whose father was a soldier named John Sullivan and born 27 Sep 1917, mother Mary Wilson. My John is definitely born 1919 as advised by my aunt who is now deceased and his mother was a Sullivan, my grandfathers sister. To confirm this I ordered his army papers which clearly give dob as "14 July 1919".b