But soon he began to yawn, and once he had started the yawns just kept on coming. Lotti was right. There was no reason to push themselves further today, especially after such an early start.

A couple of miles after leaving Emlyn Lock, they came to a lovely stretch of canal, wide and quiet, with woodland on one side and meadows on the other, where they moored for the night. They gathered wood to make a fire, and with these comforting, familiar actions Ben’s anger began to dissipate.

When the flames had died sufficiently, he brought a grill from the Sparrowhawk and put it over the embers to cook sausages.

“I’ve been thinking about Clara,” he said as he cooked. “Do you think we should have left her a note explaining what we are doing?”

Lotti, who still hadn’t forgiven Clara her own short little note, said, “She’d only come after us and try to stop us.”

The sausages, salty and slightly charred, cooked in the open air and shared with the dogs, were delicious. After they had eaten, Ben and Lotti took the dogs for a walk along the towpath until they came to a tunnel. Lotti leaned over the water to peer in, cupped one hand over her mouth and hooted. A faint echo hooted back.

“We should camp in here,” she said. “No one would ever find us.”

“Apart from all the other boats coming through.” Ben yawned again. “And you’re not allowed to stop in tunnels. It’s a law. Come on, I have to sleep.”

When they came back to the Sparrowhawk, bats were swooping over the meadow. The dogs flopped instantly asleep, but despite their tiredness Lotti and Ben stayed up on deck a little longer, unwilling to let the day go. Night fell and a barn owl sailed past like a ghost.

“A good omen,” Ben said.

Stars punctured the sky and the world felt perfect.

Ben and Lotti went to bed, intending to rise before dawn again the following day to continue their journey. But the peace of the evening, the beauty of the night, were too powerful. It was their first night sleeping alone on the Sparrowhawk and it felt delicious.

They slept late into the next morning.

How could they have known that Albert Skinner was already on their trail?

An outbreak of whooping cough at his son’s nursing home having cut short Albert’s visit, he had returned to Great Barton late on Sunday afternoon. On his way home he stopped at the police station, where he found a letter from the War Office, informing him that there had been no news of Sam Langton since he was reported missing, believed killed ten months ago.