The Chieftain Marksman (shortened to Chieftain Marksman) was one of the available chassis for the GEC Marconi Marksman turret system based on the British FV4201 Chieftain. The intention of Marconi Marksman was an anti-aircraft system solution by utilizing the existing fleets of obsolete tanks and upgrade them with a twin 35 mm turret, comparable to the Bundeswehr's Gepard and JGSDF's Type 87. The version based on Chieftain Mk 5 using Leyland L60 Mark 8A engine was tested by the British Army; the vehicle was not adopted by British Army but the turret system has been exported to Finland as the ItPsV 90 with T-55AM and Leopard 2A4 chassis.

Introduced in Update 1.79 "Project X" as the earliest radar SPAA in British tech tree. Since Update 1.87 "Locked On", the radar also allows you to lock your turret to follow a specific target and to see a "true" targeting reticle, which will guarantee a hit up to 3 km range and, on some occasions even further, even if you don't have any modifications, unless the enemy aircraft changes course. It is very important to change the keybinding of the radar lock key (default "alt + F"), as radar won't reliably lock on to targets, due to "mouse pointer" mode from "alt" button.