On Thursday, March 26, 2020 at 5:16:32 PM UTC, Another Dave wrote:
I quite fancy sitting at my desk in front of my (Linux) desktop computer
and controlling the mains lighting in my den. The existing light switch
is about 2-2.5 metres away from the computer. I envisage a substitute
light switch with a WIFI or Bluetooth controlled dimmer.

Does such a thing exist?

Another Dave
--
Change nospam to techie

Sonoff is a make worth looking at. I have put hacked firmware onto a
Sonoff S26 "Wifi Smart Plug" (search for tasmoto if the firmware interests you)

J^n