This is just a rumour at the moment nothing concrete but word is getting round that Uk ISPs are starting to blacklist popular VPN providers and their IPs.
I don’t know what the legalities of that is but it appears Virgin Media are the main protagonists in this and it won’t be long before the rest of them follow suit.
Thoughts
I don't believe it for a second VPNs are perfectly legal in the UK and they can be used for a multitude of reason`s where did you hear this rumour.