It would make sense for Virgin to do it now their brand is attached to the former NTL/Telewest and of course Virgin Mobile.
I tell you what though, I was heading up to Waterloo recently with my laptop and I set it to scan for Wifi networks - my god they were scrolling up the screen so fast it wasn't true. Some of them were open, although I'm not sure you'd get connected before you'd whizzed past and out of range.