121 (West Riding) Field Regiment RA (TA) was formed with two batteries at Bramley, Leeds in April 1939 as a duplicate of 69 Field Regiment. When 46 Division joined the BEF in France it was as a labour Division. Their support units including 121 Field remained in the UK. In February 1941 a third battery was formed in County Durham. In January 1944 121 (West Riding) Field Regiment RA (TA) was converted to 121 (West Riding) Medium Regiment RA (TA).
Illustrations of the formation badges under which a unit served or supported are given. This is no guarantee that the unit used this formations badge.
(Title authorised February 1942)
| Apr 39 |  |
46 Infantry Division | Leeds, Yorkshire, UK |
| Feb 40 | |
46 Infantry Division | Skipton, Yorkshire, UK |
| Jul 40 |  |
10 Corps | Consett, Co. Durham,UK |
| Dec 40 | |
10 Corps | Hartlepool, Co. Durham, UK |
| Jul 41 | |
10 Corps | Middlesborough, Yorkshire, UK |
| Oct 41 |  |
10 Army | Zubair, Iraq |
| Dec 41 |  |
8 Indian Division | Mosul, Iraq |
| Jun 42 |  |
10 Indian Division | Matruh, Egypt |
| Jul 42 |  |
British Troops Egypt | Deir el Shein, Egypt |
| Jul 42 |  |
British Troops Egypt | Almaza, Egypt |
| Sep 42 |  |
23 Armoured Brigade | Wadi el Saqran, Egypt |
| Oct 42 | |
23 Armoured Brigade | Alamein, Egypt |
| Dec 42 |  |
8 Army | El Adem, Libya |
| Jan 43 | |
8 Army* | Mena, Egypt |
| Mar 43 | |
8 Army | Bir Khoutine, Tunisia |
| Apr 43 | |
8 Army | Gabes, Tunisia |
| Apr 43 | |
8 Army | Enfidaville, Tunisia |
| May 43 | |
8 Army | Tripoli, Libya |
| Sep 43 | |
8 Army | Salerno, Italy |
| Sep 43 |  |
2 Army Group RA, 10 Corps | Aversa, Italy |
| Sep 43 | |
2 Army Group RA, 10 Corps | Francolise, Italy |
| Oct 43 |  |
10 Corps | Naples Italy |
| Dec 43 |  |
30 Corps | Felixstowe, Suffolk, UK |
| Jan 44 | Became 121 Medium Regiment |
* Since July 1940 the Regiment had used the Arm of Service number 2 even when it was no longer applicable. They now changed to 340.
Batteries
| Apr 39 | 275 (3rd West Riding), 276 (11th West Riding) |
| Feb 41 | 275, 276, 486 |
| Jun 42 | 275, 276 |
| Jun 43 | 161, 275, 276 – 161 Battery disbanded Jan 44 |
| Jan 44 | 275, 276 – converted to Medium Batteries |
Equipment
| Jul 42 | 16 x 25 pdr Self Propelled Bishop |
| Sep 42 | Valentine Observation Post Tanks |
| Dec 42 | Bishop exchanged for 25 pdrs (painted desert pink) |