The bike made a clicking noise pulling away from a few junctions. I got off to investigate and couldn't see anything obvious. So I carried on. At the next junction there was a loud crack. I got off to look again. Nothing obvious. I got back on, and the chain fell off. Now you can all tell me that it's disgustingly uncared for, and you'll all be right.
I've messaged the OH to ask her to drop off a chain tool at my work on the way to her work (
Decathlon is a lunch time walk away) and sent her a picture of it so you can locate the right one. I sent this image:
and received this image and a question mark in reply:
She found it in the end. Think I need to sort my tool box out a bit.