A heads up as much as anything.
Addressing a torrent of water pissing down a wall I ran for the stopcock and then found a (mercifully easily accessible) speedfit elbow had come completely unscrewed.
Anyone who has used them will know you can unscrew them partly normally to release the grip on the pipe, and entirely with a bit of force but this one offers no resistance at all until it's completely apart. And has managed to rattle/wriggle itself free.
Pics below in case you want to avoid, I would, brand looks like TLC. I've no idea where it came from oddly i've no others like it fitted or in my toolbox. So i've either bought it as a one off (doubtful, I like spares) or inherited it.