No. 8 Squadron was formed at Brooklands, just outside London, on the 1 Jan 1915, the last planned peacetime establishment Royal Flying Corps (RFC) sqn to be formed. The Squadron played an active role in World War 1, participating in some significant battles, and after the war 8 Sqn moved to Iraq and then onto Aden, Yemen in 1927. After a short period in the Far East towards the end of World War 2, 8 Sqn remained in Aden until 1967 when it moved again, this time to Bahrain. Finally, on the 21 Dec 1971, 8 Sqn was disbanded in the Middle East.
8 Sqn reformed at RAF Kinloss on 1 Jan 1972 and was equipped with the Shackleton AEW Mk 2, a long-range AEW variant which replaced the carrier-based Gannet. An interim solution whilst the Nimrod AEW Mk3 was developed.
In 1974, the British government withdrew from NATO negotiations to buy 24 American built Boeing E-3A's for a multi-national NATO AEW force which was to be based in the UK. Once Britain left the NATO project, plans for the E-3A base changed to Geilenkirchen in West Germany. With the Shackleton showing its age, and the Nimrod not yet in service, the British government again tendered for a Shackleton replacement in the mid-1980s and in Dec 1986, announced that the contract was to be awarded to Boeing to build the UK AEW aircraft. The modifications required to the E-3A to bring it up to the UK specification, gave rise to the E-3D Sentry AEW Mk 1 designation for UK aircraft. Seven of these aircraft were built and were assigned to 8 Sqn during 1991.
Three E-3D crews were trained at the NATO E-3A Component at Geilenkirchen in June 1987, to provide the foundation of the RAF's AEW crew; two of the crews formed the skeleton of No 8 Sqn with the remaining crew providing instructors for Sentry Training Squadron, which commenced training in May 1991. 8 Sqn officially received the E-3D Sentry AEW Mk1 aircraft at RAF Waddington on 1 Jul 1991. The squadron Standard was handed over to the new squadron by a Shackleton crew as the symbolic shift from ageing to modern AEW aircraft.
In 2011, one of the seven E-3Ds was removed from service as a cost-cutting exercise and is now used as a ground-based emergencies and procedures trainer at RAF Waddington.