A spokesperson said: “We are not commenting on the individuals named while that investigation continues or responding to speculation.”

But if Geddes and Shoebridge are correct, then when Anjem Choudary — Britain’s top ISIS terror recruiter — was dispatching Britons to Syria, he was, in Geddes words, “allowed… to carry on” by Britain’s security services.

The decision not to prosecute Choudary was to have fatal consequences. In February, about half of the British fighters who had travelled to Iraq, Syria and Libya returned.