Although IS is still capable of mounting local attacks using suicide bombs, its forward momentum has been checked.

IS has lost control of about 40 per cent of the populated territory it controlled in Iraq, and ten per cent of its lands in Syria. The terror group’s finances are also severely strained. The RAF and other coalition aircraft have destroyed about 30 per cent of IS’s oil infrastructure, including wellheads, ad hoc refineries, and the tankers smugglers use to move diesel and petrol.

In January, two US 900 lb bombs obliterated IS’s main cash depository in Mosul, badly affecting what is essentially an all-cash operation.

Like a shark, IS needs to keep moving to survive. In order to pay its fighters, the group is therefore more and more reliant on extortionate taxes and petty fines on a captive population of roughly seven million people which they are no longer in a position to add to.

Worse, now that Turkey (and Syrian Kurdish YPG militias) control the border with Syria, the flow of fresh foreign recruits can no longer replace the numbers of IS fatalities. A force that may have numbered between 30,000 and 50,000 has suffered 25,000 losses.

These include most of the Iraqi and Syrian Ba’athist officers who gave IS its original tactical edge in 2013-14, as well as Ali Omar al-Shishani, the red-bearded Georgian Chechen former army sergeant and commander of IS operations in northern Syria, who was killed in a US air strike in March.