The RAF’s F-111Ks were to be serialled XV902-947, the TF-111K trainers being allocated XV884-887. This speculative example, in standard RAF grey and green camouflage, carries long-range tanks on its outer pylons with a BRU-3 rack holding six Mk 84 low-drag bombs on the mid-wing stations.

Although the F-111 never entered service with the RAF, it did provide Australia with a highly effective independent strike capability from its introduction into RAAF service in 1973 until the type’s final retirement from Australian service in late 2010. These F-111Cs were photographed during Exercise Red Flag in the USA in 2006.

In December 1962 the US Defense Department placed an order for 18 pre-production F-111As for the USAF, the first of which to fly, 63-9766, is seen here some time after its maiden flight on December 21, 1964. On its second flight, on January 6, 1965, its wings were swept in flight from the minimum 16° to the full aft 72-5° position.

Two F-111Ks were under construction at the General Dynamics factory at Fort Worth, Texas, at the time of the RAF order’s cancellation in January 1968. One trainer, marked K2 on the fin, and one strike version (UK1) were some way towards completion; note the housing for the flight-refuelling probe in the upper nose section of UK1.

Another view of K2 (USAF serial 67-0149) and UK1 (67-1050) at Fort Worth. The F-111K was to use the longer wings of the US Navy’s proposed F-111B interceptor (which was also cancelled), the strengthened under­carriage of the USAF’s FB-111A strategic bomber variant, and the upgraded avionics suite of the improved F-111D.

In this speculative artwork by IAN BOTT, an RAF F-111K shimmers with condensation on the upper surfaces of its wings during a low-level sortie. When the type was cancelled for British service in January 1968, a number of RAF pilots had already got to know the type through a series of familiarisation flights in the USA.

A General Dynamics promotional artist’s impression showing a pair of F-111Ks - or possibly Merlin GR.1s - carrying an impressive load of long-range tanks and four pylons of bombs on pivoting underwing racks. The brown and green camouflage scheme, more redolent of the RAF’s Battle of Britain era, is entirely spurious.

This contemporary diagram shows the changes to the F-111A to produce the F-111K, with the RAF variant’s modifications highlighted in blue. “BFE” refers to British-furnished equipment.