The prototype Gnat first flew in 1955. The aircraft's designers had aimed at achieving the smallest possible size, low price and good performance. The Air Ministry of Britain ordered 6 Gnats for trial use. The type was not accepted into service with the Royal Air Force then, but later the RAF selected the two-seat version of the Gnat as its advanced trainer. The single-seat fighter variant was sold to Finland (13 aircraft), Yugoslavia (2), and lndia (40) where 215 aircraft were also built under licence between 1962 and 1974.
Gnats were found effective combat aircraft in the September 1965 war between lndia and Pakistan. Therefore production continued in India, where a version having internal wing fuel tanks was developed. lt was named the HAL Ajeet and 80 of it were built between 1975 and 1982. Also a two-seat version of the aircraft was developed, production beginning in 1987.
During the 1965 war with Pakistan, the Gnat is credited with downing seven Pakistani F-86 (Sabre) aircraft
The Finnish Air Force had 13 Gnats from 1958 to 1974. The first two aircraft arrived on 30th July 1958, and the following day Major Lauri Pekuri already exceeded the speed of sound as the first Finn in the Finnish airspace. One aircraft (GN-102) was already destroyed due to a technical fault on 26th August 1958. The type was grounded, and only in January 1959 did the Gnat fly again, after thorough investigations and rectifications. A public debate that had begun in the press even before the aircraft's arrival was fuelled by the accident and contributed to the fact that no more Gnats were purchased and licence production that had first been planned was not started in Finland. Many snags and deficiencies emerged in Gnats in the early stages of their service, and continuous modification work was necessary to ensure flying safety.
