Before 1941 the target tug role was undertaken by repurposed obsolete aircraft or surplus ones. However, during the Battle of Britain, the RAF saw itself lacking frontline aircraft, so, in order to avoid taking out airplanes from the frontlines, the Air Ministry asked Miles Ltd. to procure a specialized tug-towing machine.
The requirements were made official in specification 12/41. Among them there was stipulated that, in order to simplify manufacturing as much as possible, the projected aircraft should maximize the usage of standard materials whenever was possible.
The prototype flew for the first time on 24th April 1942 at Woodley Aerodrome, with satisfactory results. It was put into production shortly after and it quickly replaced the Master II production lines at Woodley factory. With 1.724 machines completed, (1.726 according to other sources) it was in production until 1945 and it served both with the RAF and the FAA in Great Britain and other parts of the world.
It was powered by a single Bristol Mercury engine which yielded up to 870 hp of power.
In Great Britain 14 Anti-Aircraft Cooperation Units employed the Martinet to train anti-aircraft gunners using a wide variety of anti-air weapon calibers. Some other Martinets served with various Air Gunnery Schools and Operational Training Units. During the postwar years Martinets served with the 2nd Tactical Air Force, based in Germany until they were replaced by Hawker Tempest target tugs in the early 1950s. One squadron, No.269, specialized in air-to-sea rescues, employed the Martinet and even a glider tug variant was developed, but not put into production.
In 1943 work began on a radio-controlled pilotless variant of the Martinet, to fulfill specification Q.10/43 which sought a Radio-controlled Fleet Gunnery Target Aircraft which could replace the Airspeed As.30 Queen Wasp. The prototype was named Queen Martinet and 65 machines were ordered. Not very much is known about this aircraft. Probably they were used in the same way as other pilotless training aircraft so they could be shot without the risk of injury to air-crew. It was also possible that they were used as targets for the very primitive air-to-air missiles. Anyway, it wasn't until March 1946 that the type was made public at an exhibition at RAF Farnborough, where it was displayed together with other captured German aircraft.
The M.37 Martinet Trainer was a prototype for a trainer version of the M.25. Back in 1941 there were considerations about a possible development of the M.19 Master but, given that it was replaced by the Martinet in most production lines, the considerations were shelved. In 1945, however, it was possible to return to the question, specially after the Air Ministry issued the specification T.7/45, looking for a three-seat advanced trainer which was powered by a turboprop engine to replace the North American Harvard (it was eventually won by the Avro Athena and the Boulton Paul Balliol) when the turboprop propellers were available. As a temporal solution, Miles proposed to convert the Martinet into an advanced trainer, as such conversion would be relatively cheap and easy, so when submitted, two prototypes were ordered.
The conversion required the removal of the outboard fuel tanks and the fitting of a revised cabin top, plus the addition of a second set of controls and instruments. The inclusion of a second-elevated cockpit provided a great field of view for the instructor, greater than that of the Harvard or the Master. It also overcame the objection raised regarding the usage of those aircraft for gunnery training as reflector sights could be installed in both cockpits. Total weight was reduced too resulting in a machine faster than both Master and Harvard and almost equal to a Hawker Hurricane.
The prototype was flown for the first time on 11th April 1946 with positive results and a second was completed shortly after. However, it was foresaw that either the Avro Athena or the Boulton Paul Balliol would be ready before the M.37 could be produced in numbers and, therefore the Martinet Trainer never went into production. Eventually, the development of the turboprop engine took longer than expected and the Balliol was put into limited production albeit fitted with a Rolls-Royce Merlin engine.
Sources:
1. https://en.wikipedia.org/wiki/Miles_Martinet
2. https://www.valka.cz/Miles-M-25-Martinet-TT-Mk-I-t11342
3. https://en.wikipedia.org/wiki/List_of_Air_Ministry_specifications
4. Scale Aircraft Modelling - vol.19 nº08 - Miles Military Trainers
5.Putnam - Miles Aircraft since 1925
