Two weeks ago, the prime minister spoke outside 10 Downing Street of the “shocking increase” in extremism and how “democracy itself is a target”. Last week, the communities secretary unveiled a refined definition of extremism, designed to ensure that the state no longer engages with suspect organisations or people. Such engagement has long been a favoured tactic of Islamists, who use the legitimacy gained through contacts with officials and other arms of the state to push their agenda.

This week, we reveal how one of the most prominent supporters of Hamas was welcomed to a reception at the House of Commons for a charity event. The head of the charity, Imam Asim Hafiz, the primary Muslim chaplain to our armed forces, is known to oppose extremism. But he was a member of a WhatsApp group that included a number of people linked with suspect organisations. There he was, not only rubbing shoulders with deeply unsavoury people at the House of Commons but participating in a WhatsApp group with them. He didn’t invite them personally. But this story illustrates the the depth and scale of the problem, not least because it shows the regularity and ease with which people who should be nowhere near Parliament end up attending functions and meetings within its walls.

It is relatively easy to lay down definitions of extremism and rules of engagement; it is fiendishly difficult to ensure that people and organisations that should be excluded from mainstream contact are indeed frozen out. Difficult — but essential.