Thanks gt, sorry if I didn't make myself clear. I knew that the BT hotspots require a login and that they must also share a portion of their own bandwidth to be able to participate in the (free) BT hotspot system. I wasn't quite sure how the Vodafone Guest System works as it seems rather more vague.
What is Guest WiFi
Guest WiFi lets you set up a separate connection to your router that can be used by your guests.
This means that guests can connect to your WiFi without needing the router password. You can also control who has access to the network, and for how long.
At first, I'd thought it was something like the BT system, but it seems not. Going off that description alone, it looks like anyone could access your network if they were close enough. Just done a quick scan locally, but no-one nearby is on vodafone broadband for me test. I wonder if that setting is enabled by default. If so then it could leave you wide open. No hacking required.
I notice Vodafone are keeping stum - quote
Vodafone told them that it did not have a record of their internet activity. It has not responded to the BBC's request for comment.
I guess I just answered my own question too. As these guest accounts are what looks like to be general guests on [your] WLAN and supposedly under your control, then they will be using your IP. So no tracking by Vodafone.
>> a guest WiFi that you can't disable
In which case it will be on by default and I bet most users wont have a clue its there. What about password control. I hope that by default its password protected because "
Choose if you want to have Password protection, and what the password will be" sounds rather ominous. I wonder how many are set up without a password and could be giving free internet access to neighbours etc.