Weird shit in the sky chat

OK, so those of you who know me are probably aware that while I accept it's entirely possible that life exists somewhere in the Universe other than Earth (the Universe is pretty big after all; and "The universe itself keeps on expanding and expanding; In all of the directions it can whizz; As fast as it can go, the speed of light, you know; Twelve million miles a minute and that's the fastest speed there is," apparently) but I'm yet to be convinced any of it visits us. So it's not that sort of weird shit in the sky chat.

However, on Thursday when I was riding back into the city at about 23:35 along Perne Road, I saw a very bright flash somewhere to the NE of Cambridge which was sufficient to light up a large part of the sky. I didn't hear anything, so if it was an explosion it was a long way off.

What's out that way that could cause such a phenomenon? So far as I and Google Earth know, there are no open-cast quarries or anything like that, which is the only sort of place I can think of that might use large explosions at night without it being all over the news the next morning.

Further Googling reveals that there is in fact a company operating some sand-excavation sites along the A10 towards Ely - so maybe it was that. I wouldn't have thought excavating sand would require explosives, but all I know about quarrying could be written in large print on a single grain of their finest.

It seems unlikely they were exploding things at half past eleven at night. That would be even more anti-social than exploding them during the daytime.

Could it have been lightning? Or a firework?

Both seem unlikely - no thunderstorms in the area, and far too big for a firework.

How much mulled wine had you had?