It was not immediately clear what may have led to the incident. Newspapers made a link to an incident earlier in the day when, during his band's set on the festival's second day, Haddon threw himself into the audience to crowd surf and injured a teenage girl, who had to be taken to hospital. Haddon immediately provided contact details in case the girl's family made a damages claim. She was later released from hospital and her condition was said to be not serious.

The idea was a good one. Napoleon feared the British would attack from the sea, as attempts at Bredene in 1798 and Walcheren in 1809 suggested. The fort is pentagonal, a form used for centuries because it gives the best outlook; two sides of the five provide a complete panorama of the horizon.

From the roof of the fort, you look out on the endless sea, and it’s easy to imagine the tense anticipation of waiting to see Her Majesty’s navy appearing over the horizon.

It never happened that way, but it might have.