Just a swift PS to the post below; it turns out that the whole infrastructure of smart gas and electric meters (new generation of which will use a common comms hub in each house that works with all power and gas suppliers plus 'enabled' appliances ..) is being rolled out by DCC Ltd, a wholly owned subsidiary of Crapita plc, now reportedly approaching a Carillion crisis. Hey ho.
There are two WAN options - one for South and Central UK and one for the North, based on radio transmission. And the documentation is interesting, confirming exactly the configuration of metallic shielding / faraday cage that will block the meters (well done, Steve) for anyone interested.
And from a skim through the technical docs, they're building in a lot of room for expanded functionality for those 'Comms hubs' - including an option for TCP/IP via packets carried on the hard power lines themselves, making wireless / radio HANs and WANs redundant.