What do you call the unelected leader of a state that beheads people in public, permits only one faith and exports an extreme form of Islam to other countries? If he happens to be Abu Bakr al Baghdadi, self-appointed caliph of Islamic State (Isis), the answer is one of the world's most wanted terrorists. If he is King Salman bin Abdulaziz al-Saud, the proper form of address is Your Majesty". Yesterday, the Prince of Wales and the Prime Minister turned up in Riyadh to pay their respects to Salman's half-brother, King Abdullah, whose death was announced on Friday. Flags flew at half-mast in Whitehall while David Cameron ... praised the deceased despot's efforts towards "strengthening understanding between faiths". This is the same David Cameron who marched in Paris two weeks ago in solidarity with the victims of al-Qaeda-inspired terrorism. Barack Obama ... found the time to praise the absolute monarch and hailed the US-Saudi relationship "as a force for stability and security in the Middle East". Few of the people hailing Abdullah as a "reformer" said anything about [how] the Saudi royal family promoted the puritanical ideology that created al-Qaeda and its offshoots, [and] sent Osama bin Laden and other young Saudis to fight in Afghanistan, creating a worldwide jihadist movement. Since then, Wahhabist ideology has inspired horrific attacks on civilians in the Middle East, Africa, the US and a string of European capitals.