As the news spread, the crack of celebratory fireworks replaced that of gunshots in Baghdad's Tahrir Square, which has been the epicentre of demonstrations since they began two months ago.

The impending departure of Mahdi is a symbolic victory for the protests, but too many people have been killed for it to quell what is close to a mass uprising by the majority Shia community. He had proved an ineffectual leader and the entire ruling elite in Iraq is probably too corrupt and too determined to hang on to power to make the radical reforms demanded by the protesters.

The announcement that the prime minister was stepping down came after 36 hours in which the security forces had switched from killing individual demonstrators to massacres on a larger scale – with as many as 50 people shot dead on a bridge in the southern city of Nasiriya – bringing the number killed to 408, as well as thousands more wounded, since 1 October.