Hi,
... I think I can add much to this topic. Ch 5 did a hit piece on the incident ... local researcher Scott Feltham is hopping mad about the way it was filmed ... and quite rightly so.
Personaly I confirmed, over a period of two years extensive research, the details of Russ Kelletts 10 yrs of research, before filming a documentary about it for him. Scott was very helpful in confirming some details.
Yes, there was an earthquake (ricther 3.

epicenter at Bala - but if you look at the BGS trace, you see there is no harmonic excitation - it is a blast profile, just like the richter 2 Buncefield oil depot explosion. I am now pretty sure exactly what caused that, where and why.
This was one of many shoot downs at that time in North Wales - simply different because a second craft was involved (seemingly trying to rescue the first) ... the first was brought down by Harriers, the second was distracted by photoflash bombs and then stunned. It soft landed nearly three miles from the wreckage of the first.
I have interviewed over a hundred local witnesses - they described to me conclusive details that they could not be expected to understand the significance of ... and they are still scared to speak of it thirty years on.
Little green men quotient, zero ... evidence of first craft wreckage - good ... Russ even had a piece before sending it off to be analysed ... also, if you look at this event - the activity started in the sea off the Welsh coast. Previously, the craft had been chased up and down the Sognje Fiord in Norway by a small task force of nato vessels. From the information Russ gathered, activity in the waterways around the coast near Bentwaters running up to this time may well have had a bearing ... and would explain some of the things Col Halt told me nearly 20 yrs ago.
best wishes,
win.