So he must have been a boy soldier. Perhaps the old regimental numbering system persisted for boy soldiers. He was discharged on 4 May 1931 under Kings Regulations para 370 (VIa) which I think is medical grounds. He would only have been around 17.
The FindMyPast transcription must be incorrect as to the enlistment date. The ledger in question covers 1919-1934 enlistments and they may have used the first year as the default if no date was stated.
