- Based at RAF Leeming, 609 (West Riding) Squadron consists mainly of RAF Regiment gunners
- Formed at Yeadon in 1936 and flew Spitfires during the Battle of Britain
- The only RAF Regiment Reserve unit in the north of England
- Supports 2 Force Protection Wing
1936 - Formed at Yeadon as a bomber squadron, and converted to fighters in 1938.
1939 - 1945 - The unit was the first Spitfire squadron to achieve 100 air-to-air ‘kills’ in World War Two. The Squadron also pioneered the use of the Hawker Typhoon in the ground-attack role.
1945 - 1957 - After the war, 609 Squadron converted to the Gloster Meteor jet fighter. The squadron was disbanded in 1957.
1998 - The Air Defence Support Squadron (ADSS) was formed, a multi-traded reserve unit in the Air Defence Role to support the Tornado F3 Wing based at RAF Leeming.
1999 - The ADSS became an Operational Support Squadron (OSS) and was granted the number 609.