My main recollections of Sea Vixens were from a project to modify some to become drones under an FR contract.
I think it was late '74 or early '75 several Vixens were delivered to Farnborough for the mods. I remember an FR test pilot flying in from Tarrant Rushton (that rather dates it) every time one was to be flown and I recall how big they looked when carrying out circuits.
On one occasion, the TP arrived as usual in an Aztec. An hour or so later, we noticed they were pushing the Aztec into the hangar along with the Vixen. Somebody phoned the 'A' Shed handlers to find out what was happening; apparently the TP had been a bit 'enthusiastic' about his planned flight and had leapt into the cockpit with great gusto and bashed his head in doing so; he was subsequently advised (presumably by our medics; we had a Medical Centre on site) not to fly that day.
I don't know how many they modded at Farnborough; there always seemed to be two in the hangar being worked on whenever I looked in and I was told they completed a total of 8; I'm not sure if they went straight to Llanbedr or whether they went to Tarrant Rushton first.