I nearly fell over as the Victory collided with a French ship just astern of the Bucentaure, and as I recovered my balance I realised just how close the ships were to one another in these sort of battles. It wasn't a cable's length – they were actually touching. The smoke of the guns swirled about us and made me cough, and the wheeezip of musket shot close by made me realise that the danger here was very real. There was another deafening concussion as the Victory's guns exploded and the French ship seemed to tremble in the water. My father leaned back to allow a large metal splinter to pass between us, then handed me a pair of binoculars.

'Dad?'

He was reaching into his pocket and pulling out, of all things, a catapult. He loaded it with a lead ball that was rolling across the deck and pulled it back tight, aiming through the swirling smoke at Nelson.

'See the sharpshooter on the most forward platform in the French rigging?'

'Yes?'

'As soon as he puts his finger on the trigger, count two and then say fire.'

I stared up at French rigging, found the sharpshooter and kept a close eye on him. He was less than fifty feet from Nelson. It was the easiest shot in the world. I saw his finger touch the trigger, and—'

'Fire!'

The lead ball flew from the catapult and caught Nelson painfully on the knee; he collapsed on the deck while the shot that would have killed him buried itself harmlessly in the deck behind him.

Captain Hardy ordered his men to take Nelson below, where he would be detained for the rest of the battle. Hardy would face his wrath come the morning and would not serve with him again for disobeying orders. My father saluted Captain Hardy, and Captain Hardy saluted him back. Hardy had marred his career, but saved his admiral. It was a good trade.

'Well,' said my father, placing the catapult back in his pocket, 'we all know how this turns out – come on!'

He took my hand as we started to accelerate through time. The battle quickly ended and the ship's deck was scrubbed clean; day rapidly followed night as we sailed swiftly back to England to a riotous welcome from crowds lining the docks. Then the boat moved again, but this time to Chatham, where it mouldered, lost its rigging, regained it and then moved again – but this time to Portsmouth, whose buildings rose around us as we moved into the twentieth century at breakneck speed.

When we decelerated we were back in the present but still in the same position on the deck, the ship now in dry dock and crowded with schoolchildren holding exercise books and in the process of being led around by a guide.

'And it was at this spot,' said the guide, pointing to a plaque on the deck, 'that Admiral Nelson was hit on the leg by a ricochet that probably saved his life.'