Following the cancellation of the planned refit of HMS Eagle to allow her to operate the Phantom, a total of 20 airframes that had originally been ordered for the Fleet Air Arm were diverted to the Royal Air Force to serve in the air defence role.
At the time, the RAF's primary interceptor was the English Electric Lightning, which suffered badly both in terms of range, loiter time and weapons fit.
These limitations which hampered its effectiveness, especially in long interceptions of Soviet Air Forces and Soviet Naval Aviation bombers and reconnaissance aircraft over the North Sea and North Atlantic.
So a new Phantom squadron was formed at RAF Leuchars, the UK's most northerly air defence base at the time, to take advantage of the improvements that the Phantom provided over the Lightning – it could carry more fuel, and had consequently better range and endurance; it was fitted with a more powerful radar; and it could carry more missiles (up to 8, compared to 2 for the Lightning).
On 1 September 1969, 43 Squadron was formed at Leuchars, operating as part of the UK's northern QRA zone alongside the Lightnings of 11 Squadron and 23 Squadron.
In 1972, when 11 Squadron was redeployed to join 5 Squadron at RAF Binbrook, it was replaced at Leuchars by the Royal Navy Phantoms of 892 NAS.

Upon the withdrawal of HMS Ark Royal in 1978, the Phantoms of the Fleet Air Arm were turned over to the RAF and used to form a second squadron at Leuchars.
At the time, 111 Squadron was stationed there operating the FGR.2 version of the Phantom, having been there since 1975.
In 1979, to save costs resulting from the differences between the FG.1 and FGR.2, the squadron converted to the ex-Navy aircraft and the FGR.2 airframes were distributed to other Phantom units.
Upon 111 Squadron's conversion to the FG.1, the Phantom Training Flight, which had been resident at Leuchars since 1972, was disbanded, and responsibility for all Phantom conversion training turned over to 228 Operational Conversion Unit.

Both 43 and 111 Squadrons retained the FG.1 until 1989, when they converted to the new Tornado F.3.
Following the standing down of the two operational squadrons and the final withdrawal of the type from service, the bulk of the RAF's FG.1 Phantoms were scrapped.
The RAF lost eight of their FG.1s in crashes throughout the type's twenty year service.
Following the cancellation of the planned refit of HMS Eagle to allow her to operate the Phantom, a total of 20 airframes that had originally been ordered for the Fleet Air Arm were diverted to the Royal Air Force to serve in the air defence role. At the time, the RAF's primary interceptor was the English Electric Lightning, which suffered badly both in terms of range, loiter time and weapons fit. These limitations which hampered its effectiveness, especially in long interceptions of Soviet Air Forces and Soviet Naval Aviation bombers and reconnaissance aircraft over the North Sea and North Atlantic. So a new Phantom squadron was formed at RAF Leuchars, the UK's most northerly air defence base at the time, to take advantage of the improvements that the Phantom provided over the Lightning – it could carry more fuel, and had consequently better range and endurance; it was fitted with a more powerful radar; and it could carry more missiles (up to 8, compared to 2 for the Lightning). On 1 September 1969, 43 Squadron was formed at Leuchars, operating as part of the UK's northern QRA zone alongside the Lightnings of 11 Squadron and 23 Squadron. In 1972, when 11 Squadron was redeployed to join 5 Squadron at RAF Binbrook, it was replaced at Leuchars by the Royal Navy Phantoms of 892 NAS.
Upon the withdrawal of HMS Ark Royal in 1978, the Phantoms of the Fleet Air Arm were turned over to the RAF and used to form a second squadron at Leuchars. At the time, 111 Squadron was stationed there operating the FGR.2 version of the Phantom, having been there since 1975. In 1979, to save costs resulting from the differences between the FG.1 and FGR.2, the squadron converted to the ex-Navy aircraft and the FGR.2 airframes were distributed to other Phantom units. Upon 111 Squadron's conversion to the FG.1, the Phantom Training Flight, which had been resident at Leuchars since 1972, was disbanded, and responsibility for all Phantom conversion training turned over to 228 Operational Conversion Unit.
Both 43 and 111 Squadrons retained the FG.1 until 1989, when they converted to the new Tornado F.3. Following the standing down of the two operational squadrons and the final withdrawal of the type from service, the bulk of the RAF's FG.1 Phantoms were scrapped. The RAF lost eight of their FG.1s in crashes throughout the type's twenty year service.
McDonnell Douglas Phantom in UK service