100th (Yeomanry) Regiment Royal Artillery is a British Territorial Army Royal Artillery regiment that has three gun batteries, all equipped with the L118 Light Gun.
289 Parachute Troop has a prestigious and proud history, being its own regiment in 1956 (289 Parachute Light Regiment Royal Horse Artillery) The unit was initially formed as the 289th Parachute Light Regiment, Royal Artillery in 1956, from an amalgam of the post-war Territorial Army 16 Airborne Division Artillery units. These were 291 (4th London) Airborne Field Regiment RA (TA) (based at Lewisham), 292 (5th London) Airborne Anti-Tank Regiment RA (TA) (based at Kensington) and 285 (Essex) Airborne Light Regiment RA (TA) (based at Stratford).
289 Para Lt Reg RA was named from the fusion of 285 and 291 and formed in 1956, initially becoming part of 44th (Independent) Parachute Group (TA), equipped with 4.2" mortars. It was renamed to 289 Parachute Light Regiment, Royal Horse Artillery in 1961/62 (around the time 33rd Para Light Regiment Royal Artillery became 7th Parachute Regiment RHA), and assigned new weaponry, chiefly the 25-pounder field guns after the 4.2" ammunition had been found deficient. RHQ was at Highwood Barracks, East Dulwich, with P Battery at TA Centre, Romford, Q Battery based at Hollyhedge House, Blackheath and R Battery at Chingford, Essex.
289 Light Regiment was revised and redesignated 289 Parachute Battery, Royal Horse Artillery (V) in 1967. The Battery was renamed and left 44th Parachute Brigade in 1977, when transferred to 29 Commando Regiment RA and became 289 Commando Battery, RA (V). The line of Airborne service has continued to the present however, with 289 Parachute Troop RA, which is now part of 201 (Herts and Beds) Yeomanry Battery RA (V), 100 Regiment Royal Artillery (V). 289 Parachute Troop supports the regular 7th Parachute Regiment Royal Horse Artillery.