At the North West London Jewish Day School in Willesden, the five-year-olds are being taught how to respond to a terrorist attack.
“We have regular drills for the children, and they know how to recognise the different alarm signals,” says Daniel Kerbel, the head teacher. There is a permanent security guard on the premises, and each of the classrooms has been fitted with new locks so they can be “invacuated”, their doors secured from inside to act as last-ditch defences between the pupils and a killer.
A few miles to the north, the Jewish Community Secondary School in Barnet, JCoSS, is protected by a security gatehouse and Downing Street-style car-bomb barriers.
In the wake of the anti-Semitic murders of four people in Paris, anxiety has risen so high that some parents have taken to social media, questioning the presence of Muslim cleaners at the school.