I don't think he ever arrived to attest. The Alphabetic Register entry does not give any details of rank, age, regiment. Not on Numneric Register
1921 Mar 15. ADRIC no 1866. The entry just says Depot Coy. And no date of discharge. Not on Numeric Register
There was a John Edward Hunter in RIC who retired in 1 Nov 1920 as a Sgt. I have no way of knowing if this is the same man