| September 1940 | CO: Lt Col JAL Powell |
| Sep 40 | North Irish Horse |
| 1/9/40 | Portrush Capt OC Smith-Bingham relinquishes appointment of Adjutant, Capt J Rew assumes appointment. |
| 2/9/40 | 2Lt ECS Hargreaves posted to No. 2 Commando. |
| 4/9/40 | Lt JAO Walker to be A/U/Capt wef 19/8/40. |
| 6/9/40 | Lt P Alban RAOC attached with No. 4 LAD. |
| 9/9/40 | A/U/Capt Walker made A/Capt wef 19/8/40. |
| 12/9/40 | Capt OC Smith-Bingham posted to MSC Camberley whilst attending No.4 Junior War Staff course. |
| 20/9/40 | FGCM held on Tpr Napier on charges under AA 32(1) and AA 40. Judge Advocate was present in court. |
| 23/9/40 | Regt took part in 61 Div Exercise. |
| 24/9/40 | Finding of FGCM on Tpr Napier promulgated detention for 84 days. |
| 26/9/40 | His Grace the Governor of Northern Ireland, The Duke of Abercorn KG KP visited the Regt. |
| 27/9/40 | Regt took part in 61 Div exercise. |