Commemoration of atrocity at Nova music festival confronts those who deny its gravity, says Elkana Bohbot

Two police vans waited expectantly near the front entrance. Officers patrolled the pavements while suited security men with ear pieces stood stern-faced, casting suspicious looks at those approaching. The location in east London had not been disclosed until that morning but no chances were being taken.

It was not for a visiting dignitary or even an embassy of a country in conflict that all this was deemed necessary but the Nova exhibition, a commemoration of the 378 people massacred at a music festival on 7 October along with the 44 taken as hostages and the 19 of those who died in Hamas captivity.