“What has helped Maliki is Daash,” said a policeman in Baghdad who declined to be named, referring to IS’s Arabic acronym.

“It has allowed him to rally Shiites behind him. He knows now he can’t rely on the army.”

The militants’ advance was so rapid it prompted the rare call to arms by Sistani, triggering a massive mobilisation of Shiite volunteers and fighters.

Crucially, the octogenarian cleric was careful to specify that any fightback must be under the auspices of the security agencies, infusing Maliki’s forces with — in the eyes of some Iraqis — religious legitimacy and fighters enthused with sectarian fervour.

Sabah al-Kaabi, a 43-year-old tailor at a barber shop in the capital, said: “What has rescued Maliki is Sistani. If it wasn’t for that, Maliki would have had to flee Baghdad.”