100th (Yeomanry) Regiment Royal Artillery
|100th (Yeomanry) Regiment Royal Artillery|
|Garrison/HQ||Army Reserve Centre, Luton|
|Equipment||L118 Light Gun|
Two of the founding Battery's HQ Home Counties and 202 Battery can trace their origins back to pre Union as evidenced in the 106 Regiment Officers Mess.
The Regiments original role was BAOR emergency reinforcement, emphasised by its transfer into 49 infantry brigade part of 2 Div. Under options for change the Regiment became a general support regiment fitted out with the 155 towed FH70 gun and assigned to 3 Division, in 1999 it was reassigned as a CS Regiment, losing its ability to deploy as a whole Regiment.
The regiment was formed as 100th (Eastern) Medium Regiment Royal Artillery at Grove Park in London in 1967. Its units were RHQ, HQ (Home Counties) Battery at Grove Park, 200 (Sussex Yeomanry) Medium Battery at Brighton, 201 (Herfordshire and Bedfordshire Yeomanry) Medium Battery at Luton, 202 (Suffolk and Norfolk Yeomanry) Medium Battery at Bury St Edmunds and REME LAD which expanded to workshop during FH70 period.  In 1970 the regiment became 100th Regiment Royal Artillery and in 1976 it became 100 (Yeomanry) Field Regiment Royal Artillery. In 1993 200 Battery left the regiment and 307 (South Nottinghamshire Hussars) Battery at Bulwell joined the regiment. It was renamed 100 (Yeomanry) Regiment Royal Artillery in 1993 and, in 1999, HQ and 202 Battery's left the regiment, 202 were replaced by 266 (Gloucestershire Volunteer Artillery) Battery at Bristol.
The batteries are as follows:
- 201 (Hertfordshire and Bedfordshire Yeomanry), based in Luton, to be placed in suspended animation under Army 2020.
- 266 (Gloucestershire Volunteer Artillery), based in Bristol, currently use the 105mm Light Gun in support of 29th Commando Regiment Royal Artillery. Under Army 2020, this battery will subordinate to 104th Regiment Royal Artillery and will re-role to mini unmanned air systems.
- 307 (South Nottinghamshire Hussars) Battery, based in Bulwell, to be placed in suspended animation under Army 2020.
- King Carl XVI Gustaf of Sweden until 2001 (Moved to 106 Regt)
- Major General Freddie Viggers, ? to 17 February 2001 
- Major General Andrew Ritchie, 17 February 2001 to present
- "Royal Regiment of Artillery, Volunteer Regiments". Retrieved 11 May 2014.
- Summary of Reserve Structure and Basing Changes
- "100 Regiment RA". Ministry of Defence. Retrieved 11 May 2014.
- The London Gazette: . 2 April 2001. Retrieved 2012-07-23.