Almost certainly because I have a guest next week, the house infrastructure has started playing up.
The Hive hub is offline: https://www.hivehome.com/in-app/hubs-not-talking. Luckily though the heating and hot water seems still to be working on its set up schedule.
There's a very slow leak into the bathroom toilet. It looks to me like the float valve is wearing out. Swapping that looks a bit above my pay grade, perhaps I had better get Silver Saints on the job.