It might just be a virgin media thing but I cannot browse to any vpn sites but the filtering is done differently the porn filter i.e. it's by government request but not publicly enough to warrant a redirect to their site
I swapped to TalkTalk recently and have the same problem. All but the most obscure VPN sites are blocked. My guess is because using them is aginst TOS?
Have you checked that you've turned off any "parental controls". I believe by default, new connections come with a "family friendly" filter. And that includes VPN services, since (presumably by their logic) VPNs are the first thing a kid will download to get around this filter...
