The Iraq War was never a liberation of any kind, but was a US invasion, which led to diverse but extensive local resistance bolstered by foreign fighters. A tool of the US occupation (with Britain in tow) was the execution and torture of opponents.
True, Britain may have initiated torture independently. The torturing to death of Baha Mousain 2003, seemingly for pure sadistic pleasure, is one such case. Yet, the fact that British hands are contaminated with this filth, flows for the most part from Blair’s decision to collaborate in Bush’s crime: the invasion of Iraq.