Are you sure you have enough spare network ports there?

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The solutions by Hades/York would be the best and most reliable way I imagine (do they do a UK plug version though?).
If you really want to go for a hacky solution then you could still use infra-red. This may work:
- Buy infra-red powered plugs, e.g. these for £4.35 - you can program each plug with your own infra-red command from an existing remote or whatever.
I actually use a free LIME infrared plug I got sent to turn a powerstrip with my TV/AV receiver etc on from my Harmony remote, works very well
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- Buy a USB Infra-red Toy v2 for £11.83 from here
- Use WinLIRC to send the IR commands to the infra-red plug you want to power on/off (you can learn the correct IR code from the remote you used earlier)