It looks like Wikipedia has fallen-foul of the long reach of the Internet Watch Foundation, which has decided to block pages on it.
The main offending page is dedicated to the rock band The Scorpions album "Virgin Killer", which featured on its original 1976 sleeve a pretty tasteless image of a naked pre-pubescent girl. Try and access this page from many UK ISPs at the moment, and you'll get an error message telling you it was "not found on this server". In fact, it is on the server – you're just not allowed to access it.
The issue first came to attention when it was noticed that a large
number of UK ISP users were coming from a single IP address, including
all of those from my own ISP, Be Unlimited. This address was used to
spam Wikipedia, and so got blocked – leading to thousands of people
unable to edit articles or create new user logins.
The discussions of this on Wikipedia suggest that what's happening is this: once a site has been notified to the IWF as containing child pornography, traffic to it is filtered through an invisible proxy, and offending pages are silently blocked with what looks like a legitimate 404 error. Not all UK ISPs use the same system for filtering and blocking, which explains why some users can still get to page.
However, it's very easy to route around this: within about five minutes of reading about it, I'd found three ways to get to the offending page (which is how I know what album they're talking about!). None of them involve anything complicated, but instead simply substitute alternate URLs. No one actively looking for child porn would be stopped by this.
And, in fact, some ISPs acknowledge this when they talk about how they use the IWF blacklist. Demon, for example, talks about it stopping customers from "accidentally viewing illegal child abuse imagery", rather than it preventing a committed paedophile.
The IWF doesn't comment on individual cases, nor does it notify those responsible – which is why it appears that Wikimedia has not been told it is now being filtered. There is an appeal process if you get on to its censorship list – but obviously, it's fairly difficult to appeal if you don't know you're being filtered.
The IWF has performed a good and valuable function in helping to get rid of real child porn sites hosted in the UK. But this issue with Wikipedia is troublesome: there is no transparency and no notification even when the site involved is one as widely-known and valued as Wikipedia. The appeal process ultimately relies on the judgment of the police as to what might be pornographic, rather than an experienced prosecutor – and the police are, of course, inevitably (and generally rightly) going to be reluctant to allow any image which even potentially could be regarded as child porn.
We need to deal with the issue of child porn seriously and effectively – and silent black lists created by unaccountable bodies with no judicial oversight is not the best way to do it. It's a typically British form of censorship – quietly done, swept under the carpet, in the hope that no one will notice. Bill Thompson described it best four years ago, when he wrote about BT's Cleanlist: "It is censorship, but it is a typically embarrassed and underhand British form of censorship". Bill also said this:
"Because the announcement is about child abuse, anyone
who dares to challenge it is instantly under suspicion as a supporter
of paedophiles. But this should not stop us pointing out that Cleanfeed
is a bad idea and must be stopped.
This is not just because it will not achieve its goal,
although it seems that it will be easy to get around, but because it
sets a precedent for ISP control over what their users can do online
that is simply unacceptable"
Bill was right then, and he's right now. And this case with Wikipedia should, at least, bring some of these issues into the light.
Update – More coverage: