Radar, Anti-Aircraft, or simply AA radar for short, was a classification system for British Army radars introduced in 1943 and used into the 1960s when these systems were replaced by missiles with their own integral radar systems. The classification included subcategories, Number 1 through 8, as well as the many individual systems which were assigned Marks. Some of the Army radars pre-date the introduction of this classification system and had their own nomenclature that tended to remain in use even after they officially received new names. Notable among these are the Gun Laying and Searchlight Control categories. Additionally, equipment introduced after the classification system often have rainbow codes that they are well known by. Some were also used by the Royal Air Force and thus also had an AMES number. Number 1 AA Number 1 was assigned to the early gun laying radars operating in the 1.5 m VHF band. They were almost always referred to by their original name, GL Mk. I radar. The microwave-frequency systems that replaced them were assigned Number 3. There were three entries in the Number 1 classification: AA No. 1 Mark 1 - GL Mk. I AA No. 1 Mark 1* - GL Mk. I*, a slightly upgraded version of the original AA No. 1 Mark 2 - GL Mk. II Number 2 AA Number 2 was assigned to the existing Searchlight Control radars. There were nine entries, Mark 1 through Mark 9, which were identical to the original Marks of the original SLC category and differed only in their mounting systems. The SLC concept was already falling from use when the new naming system was introduced, and they were generally not referred to by their new names. Number 3 AA Number 3 collected a wide variety of microwave-frequency gun laying radars, mostly following the Marks of the earlier Gun Laying category. This was one of the few categories that was used extensively in the post-war era, and thus one of the few that contains entries without a former GL name. There were eight entries: AA No. 3 Mark 1 - GL Mk. III(C), the Canadian-designed version of Mk. III. AA No. 3 Mark 2 - GL Mk. III(B), the UK-designed version of Mk. III. Sub-versions /1 through /5. AA No. 3 Mark 3 - Expedient portable AA radar based on the SLC electronics. Also known as "Baby Maggie". AA No. 3 Mark 4