Wow, that's some pretty strong purple liquid. Any hunches as to what it might have been?
No idea, but it sounds like it wasn't just the liquid, it's the fact that it vaporized in a confined space, and then was sparked by something like a stove pilot, or perhaps a second, time-delayed reaction (think a cigarette in a matchbook) ignited it. That's a FAE, which has tremendous power. Any flammable distillate can have that effect if conditions are right. This is from Fox, which said "mailbox", BBC said "mail slot", which is probably correct and means it was inside the home to become a rarified air-mixed vapor. Kaboom.
It's why gasoline vapor in a mostly-empty tank is so much more dangerous (it will explode violently) than a full tank, which will just burn.
I've seen firsthand what happened to a muffler shop where a propane tank had been leaking overnight, filling the shop with a propane-air mixture. Poor guy came there in the morning, turned on the lights, and the store, well...after a massive groundshaking blast and a mushroom cloud that went several hundred feet up, all that was left was a few standing i-beams, the rest was scattered over a mile.
What's thrown me is the "girl gangs" thing. I had no idea London had female Clockwork Orange sorts who blow up houses!
