| May 1940 | CO: Lt Col JAL Powell |
| May 40 | North Irish Horse |
| 3/5/40 | Enniskillen 2Lt RD Morton joined the Regt and was posted to C Sqn. |
| 4/5/40 | Lt JA Heanen RAOC appointed Technical Officer vice 2Lt RJ Adams. |
| 6/5/40 | Lecture on the German Army by Colonel AJ McGrath DSO. |
| 14/5/40 | Mobile column to recce for any available air landing grounds. |
| 15/5/40 | CO proceeds to England on duty. |
| 17/5/40 | Tpr Keville WA tried by DCM on a charge under AA 18(4). Mobile column ordered at one hour's notice. |
| 18/5/40 | 30 ORs proceeded to Belfast to attend D&M course. |
| 20/5/40 | DCM on Tpr Keville promulgated and sentence of 56 days detention awarded. |
| 24/5/40 | Threatened action by IRA. Mobile column and ACs ordered to stand to. Officers to live in barracks. Not less than 50% to be permanently in barracks and all guards doubled. Regtl strength Officers 16, WOs 9, Sgts 30, ORs 470 |
| 25/5/40 | Major Sir R Ross Bt MC, MP, relegated to unemployed list. |
| 28/5/40 | Restrictions on officers and ORs and on patrols and piquets rescinded. |
| 30/5/40 | Lt H Petch DCM, 11th Hussars joined Regt and posted to B Sqn. Lt JA Stewart, RTR, joined Regt and posted to HQ Sqn. |
| 31/5/40 | 2Lt ECS Hargreaves, RTR, joined Regt and posted to A Sqn. 2Lt PR Kitto, RTR, joined the Regt and posted to C Sqn. |