Another week, another revolution. President Muammer Gaddafi of Libya may soon become the third Arab president to be swept from power in little more than a month.

Until a few years ago, his toppling would have been greeted with delight in western capitals. But in recent years, the Libyan leader has been recast as a reformed sinner, an ally in the “war on terror” and a valued business partner. His current travails should be a cause of justified embarrassment – not least in London – since Britain has led the way in the attempted rehabilitation of Colonel Gaddafi.

Changing attitudes to the colonel highlight the way in which western concern over human rights is almost always coloured by convenience. In the 1980s, the Libyan leader was regarded as the foremost state sponsor of terrorism and rightly denounced for his dreadful human rights record. Ronald Reagan called him a “mad dog” and the US bombed Tripoli in 1986. Saddam Hussein of Iraq, by contrast, was largely tolerated because he was useful in containing Iran.