There are no sign of a St.John John or a John St.John in WO338. There was no "intake" to ADRIC on 15 April 1921, so his entry was different again pointing to Irish. He was in fact John St John, who joined the RIC in 1880, was pensioned in 1920, and then was taken on as a Paymaster for Depot Company
He is not on Numeric Register
1860 Apr Born Tipperary (RIC)
1860 Apr 18 Bapt at Moycarkey
1880 Dec 10. Enlisted in RIC
1888 Jan 14 Married in Killarney to Mary O'Sullivan
1920 Sep 1 Pensioned from RIC as a Head Constable
1921 Apr 15. Joined ADRIC as Assistant Paymaster at Depot Coy with service no 1923. No details of age, regiment. He appears to have served in RIC through WW1
1921 Apr 15 Appointed as Assistant Paymaster in U.D.R.S.C at £250 per year. He appears to have gone to Ulster Special Constabulary
1921 Nov 30. Struck off strength on ceasing to be employed as Paymaster.
1925 Dec 3. Died Dublin