(Neither a pilot then nor now but.....)
Wasn't the version of the Phantom brought for the RAF (F4M or FGR.2) specifically ordered with a radar for use with the SUU-23A pod, unlike the F4K (FG.1) which was brought without?
Wouldn't this show the RAF had a perceived want/requirement for a cannon-armed version rather than a happy coincidence that someone else wanted it and came as part of the package?