We followed them to the fence along the waterfront, to find all eyes fixed on a small launch, barely bigger than a rowing boat, battering at speed through the waves. Steered by a young man, it shot eastwards towards the open sea. These attempts never happened in London because the Thames was too well defended there, but outside the capital people tried from time to time to escape by water. I had heard of night-time bids to slip from Herne Bay around the coast, although I had no idea if they were ever successful.

Everyone was watching the boat, willing it on. Above us, harsh searchlights picked out the launch, making the waves glitter. Then three cracks split the air and I looked up to see a guard in the watch tower lower his rifle.

I stared out to see if the young man had been hit. We all did. But the boat was still moving – the guard had missed. I felt my heart lift as if I were in the little vessel with that young man putting his life at risk to get to a northern shore. From the west, one of our patrol boats appeared, racing in his wake, hugging the shoreline.

‘Will he make it?’ I asked Tibbot, putting aside, for a moment, our own purpose that afternoon. But it struck me that our task wasn’t unconnected to this sight. Whatever had, ultimately, pushed this young man to speed between air-cutting bullets in the Thames Estuary was surely the same cause that had left Lorelei shimmering under cold, drifting water in London. ‘If he can get to the middle, he might. That’s where the mines are – our boat won’t follow.’

He was only a few hundred metres from the centre line. It couldn’t take him long.

‘Won’t he set off the mines himself?’

‘Maybe little boats don’t set them off. I don’t know.’

The people around us were egging the pilot on. The men in particular were shaking the wire fence. The children kept trying to climb the links but were dragged down and slapped by their parents, who pointed to the watch towers that were spitting more and more bullets.

‘Will he get through?’ I asked aloud.

‘Yes!’ a young man shouted back, abandoning discretion. Another patrol boat roared in from the east, but they were both holding back.

‘What are they doing?’ I said.

Tibbot jerked his thumb to the towers. ‘Too many rounds. They don’t want to get hit themselves.’ The young man kept changing his course, apparently trying to make it harder for the soldiers to aim.

‘He’s going to do it!’ shouted one of the men. But, just as he did so, there was another volley of gunfire and the pilot disappeared from view.

‘Did he fall in?’ cried one of the women.