The UK has long prepared the way for the troop reductions from Iraq – announced on Wednesday – by emphasising how different conditions in the south of the country are from those in the centre where a surge in US forces is under way.

The Shia-dominated south has not witnessed the ­violent Sunni insurgency that has riven Baghdad and the rest of central Iraq. But it has, nonetheless, seen in-creasing levels of violence as Shia militias have competed for spoils.