truth is I don't think anyone will really know what it was..unless the sound occurs tonight or over the coming weeks
I've been on the receiving end of many: it sounds nothing like 'em. There's just an enormous bang, and all the windows shake. I reckon it's trapped wind.
We've had the ability to actually record noises for maybe 100 years yet people (not here) are saying this is unprecedented.... Anyone asked the geo phys people, the ones that record earth quakes, if there had been anything on their kit? If there isn't how do we know that it's not a natural phenomenon anyway, again, there seems a weird habit of anything unusual in the living memory of one generation as man made...
I've solved it: www.dailymail.co.uk/news/article-2854551/What-loud-bangs-heard-Britain-Twitter-bombarded-reports-mysterious-noises-military-denies-RAF-jets-cause.html
latest crap on the radio this morning said it was some sort of pulse jet fighter that can travel 5x the speed of sound - top secret thingy or summat.
yep the Aurora, uses combustion engines that produce some sort of vortex exhaust trail and can travel at Mach 6 (the RAF have tracked it over the north of Scotland in the past). The parent company of HBM (my employer), Spectris PLC used to be part of Fairey Aviation Hydraulics who did the hydraulic systems of the SR71 and A12 Stealth Bombers, back in't day