Re: Doesn't BT already do this in the UK?
First thing that occurred to me, the BT homehub does this and has done for several years now.
I went to Virgin to avoid BT as their shared wifi homehub bothered me. I took VM's shitty Superbhub and put my own kit behind it so the scumbag's router is on a different subnet from my internal network and I firewall them outside. They're more than welcome to go into their superhub and even watch the traffic passing through but their not getting in to snoop directly on what I've connected.