The AS-90 (Artillery System for the 1990s; known officially as Gun Equipment 155 mm L131) is a lightly armoured self-propelled artillery piece used by the British Army.
The AS-90 was first deployed by the British Army in 1993. 179 AS-90s were acquired to re-equip six of the eight self-propelled field artillery regiments (each 24 guns) in the 1 (BR) Corps, replacing the 105 mm FV433 Abbot SPG and older M109 155 mm Self Propelled Gun. It remains in UK service and will equip three field regiments supporting armoured infantry brigades for the foreseeable future. 134 in service in 2008, 117 in 2015.
AS-90 was designed and built by the Armaments division of Vickers Shipbuilding and Engineering (VSEL), whose parent company became BAE Systems in 1999. VSEL provided 179 vehicles between 1992 and 1995 at a cost of £300 million ($480 million USD).
The AS-90 underwent a capability enhancement program in 2008 and 2009, primarily relating to upgrades of the AS-90's electronic system.
In 1999, Marconi Electronic Systems was contracted to upgrade British Army AS-90s to include a 52 calibre gun in order to increase the range of the artillery. Critical to the program was a bi-modular charge system from Somchem of South Africa (selected after extensive trials of ammunition from many suppliers), which offered greatly reduced barrel wear. However, this ammunition failed to meet the requirement for insensitive munitions and the project was terminated.
Information from Wikipedia