Danny, no doubt those on duty at Valley and Prestwick suffered similar feelings of angst as you in making their observations official.
A colleague of mine was flying into a deserted London area down R1(?) from CLN at 00 very early hours. He and his Herc crew saw a bright light that wasn't moving relative to them. It wasn't Venus or any of the usual heavenly bodies. Tentatively he called ATC and asked if they had any traffic in his vicinity. "Negative", came the reply. "Well we have something on a constant bearing showing a bright light and...", at this point the light source took off at an incredible rate, now moving in an accelerating arc across their intended track, "... now it's changed direction and accelerating away out of sight", he finished lamely. London, using that polite note of dubiousness which airtraffickers are no doubt taught in training repeated that he had no known traffic that was aware of or could see. Luckily a USAF pilot bound for Mildenhall confirmed the sighting, so an official report was filed on arrival.
The following morning his crew was told to report to MOD London to be debriefed. Having told all and sundry of their sighting previously, they now had no comment to make whatsoever...
As you say, Danny, strange lights seen can seriously affect one's career!