I wonder if it used X10? If so it could still be integrated with home assistant.

I would (hate|love) to see one of our setups built with 1980’s tech. Imagine the yellowed white (and red) boxes and bulky everything

I’ve not been able to find much out about this, but they do have one at the CfCH in Cambridge. https://www.computinghistory.org.uk/det/36892/BBC-Micro-Red-Box/