After contacting Custom Solutions Inc in Florida I discovered they were just finalising a "UK beta" version of their HomeVision controller. It's a beta because it hasn't been tested here in the UK yet…
A short time ago I installed a WinTV/PCI card from Hauppauge. This week I finally got round to cabling the UHF into the computer room so now as well as getting TV in a window on my monitor I can see the baby's room via the CotCam...
OK...my TW523 two way power line interface arrived in the post this morning. This now allows me to connect my PC to the mains via the serial port (this sounds very dodgy!). Reading the blurb I am assured that the unit is "Opto-Coupled" which presumably means at some stage in the circuit the electrical connection is replaced by light to ensure the mains will never actually reach the serial port...