LONDON – If parliamentary politics were a simple yes and no business, as in a referendum, British Prime Minister Tony Blair would be out of office by the end of the week. It’s a subtle process, as it should be, and his party, bruised though it is by being seriously misled on the reasons for going to war in Iraq, is apparently not yet ready for it. Still, after the publication of the latest report – authored by Lord Butler, a former head of the UK civil service – that has plumbed the murky world of intelligence and the office of the prime minister in the decision making that led up to the Iraqi war – historians if not yet parliament are already fashioning their judgments. Anthony Seldon, author of a recent biography of Blair, has observed, “No prime minister in the last 100 years has added to their achievements after...