Yes I read it. There's another by the same journalist: Prostitution and trafficking ? the anatomy of a moral panic | UK news | The Guardian, which talks about where the numbers usually quoted in the media come from.

Both are interesting. One minor quibble is that the title of the one you linked is a bit misleading. There have been traffickers convicted in the UK recently. And I mean real traffickers rather than the UK's warped definition. It's just that they weren't caught by the overhyped Operation Pentameter. Nick Davies isn't disputing that, but you have to read the whole article to find out. I think he couldn't resist the temptation of a shocking title.

For those who won't bother to read the full articles, here's a one sentence summary: Trafficking happens, is hard to measure accurately, and is almost certainly much rarer than the media usually suggests.