| December 1940 | CO: Lt Col JAL Powell |
| Dec 40 | North Irish Horse |
| 4/12/40 | Portrush 2Lt CA Crofton to be A/U/Capt. |
| 7/12/40 | 2Lt RS Hutton, 2Lt CM Thomas and 2Lt PCM Sinclair joined on first commission. |
| 10/12/40 | 2Lts RSH Sidebottom, TM Batchen, ES Robinson and S Walker joined on first commission. |
| 16/12/40 | 7902429 Cpl H Kennedy received fatal injuries in motor accident. |
| 17/12/40 | Lt WWG Lavery joined the Regt. |
| 20/12/40 | 2Lt JD Dunlop joined the Regt. |
| 23/12/40 | 2Lt PPP McCraith joined the Regt. |
| 25/12/40 | A/Capt CA Crofton granted pay of rank wef 4/12/40. |
| 30/12/40 | CO proceeded on leave and command was assumed by Major D Dawnay. |