R Barrett or R Barnett

I cannot get him in RIC Register, without this, it cannot be solved

1921 Jan 21 Joined ADRIC with service no 1577. Posted to F Coy. Accepted in Ireland

Fined 10/- by Coy Commander

1922 Jan 19. Discharged on demobilisation of ADRIC

Palestine Police

He has no Regt and no age, not enough clues to get anywhere.