The downside being……?
British jihadists caught fighting with Isil in Mosul could be handed death sentences in makeshift Iraqi courts trying up to 100 suspected terrorists a month.
Iraqi authorities are screening all men of fighting age as they flee Isil-controlled areas in the offensive to liberate Mosul.
They check their names against a database of wanted suspects, collated from information passed to them from residents inside Mosul as well as their own records.
There are nearly 40,000 names on the list, 80 per cent of them in connection with terrorism.
It can be an arduous process, particularly when the suspect has a common name. And many get wrongly caught in the dragnet.
Those who are deemed to warrant further investigation are kept in makeshift prisons in houses and mosques around Qayyarah, 40 miles south of Mosul, pending either release or trial.