Long-term followers of the great Internet child-porn debate will be unsurprised that some confusion has followed BT's announcement that it has blocked hundreds of thousands of attempted accesses to naughty sites. Much about the Cleanfeed Web filtering system seems unclear -- BT says that it actively decided not to record who fell foul of the blocker, but as it is legally required to pass information on all Web accesses to the authorities under RIPA, this decision may make no difference whatsoever. In any case, you can be sure that the authorities will have demanded this information -- or may be scanning logs to find it out in any case. Also, it would be remarkable from a technical point of view if the people within BT who implement Cleanfeed don't keep logs to see how it's working, where the chokepoints are, and what the patterns of usage are telling them about how to enhance or fine-tune the service.
And then there's the question of what an access actually is. One click on a link can result in many access requests to a server -- even if the page that you're trying to look at isn't on that server. The wild world of online porn is particularly bad at this, with many sites embedding adverts and images on each other's pages. And most of the trade in the nasty stuff is taking place elsewhere on the Internet anyway -- IRC, FTP and P2P being nicely decentralised, uncontrolled systems that don't lend themselves to monitoring or blocking.
So from BT's announcements, we know almost nothing except that certain sites were blocked and some traffic stopped. Who created that traffic -- groups of dedicated pornhounds, hapless surfers clicking on spam at random, even people trying to mess up BT's statistics -- we cannot tell. What impact is it having on the amount of child porn circulating? Your guess is as good as mine: mine is not very much.
So when a gaggle of MPs get together to say things like BT's efforts are "an important deterrent to those accessing child pornography material on the Internet", the only sane response is "Maybe." If it's doing no good, then the effort and publicity should go towards something that does work: if it's working well, then BT deserve support. But we have to know which of the two it is -- headline figures and flagwaving do nobody any service.