The result, so far as Britain is concerned, is that the leaders of the Islamic State of Iraq and the Levant (Isil) have succeeded in setting up a network of sleeper cells throughout the UK which can be activated to conduct terrorist attacks on a similar scale to those recently experienced in Paris and Brussels.

In short, to use the terminology familiar to MI5 and MI6 officers, Isil leaders have succeeded in “weaponising” the refugee crisis for their own nefarious purposes.

James Clapper, the US Director of National Intelligence, earlier this week revealed the existence of sleeper cells in the UK, as well as other European states such as Germany and Italy. He believes Isil has been able to infiltrate the country by taking advantage of Europe’s porous borders.