1920 Oct 7. Joined ADRIC with service no 1836
CO of P Coy at Tubbercurry
1921 May 15. The Captain was fired on by the IRA when he was on his way from Easkey to Tubbercurry at Gleneask. His car was hit five times but he escaped injury.
1922 Mar. P Company's Accounts were missing £535, Johnstone having received it as a temporary advance from the commander of Depot Coy. Johnstone told the company paymaster that he had repaid the advance "it has now been ascertained that this is not the case". The Amy then took steps to withold a compensation payment to Johnstone for injuries he had received on duty