The house is about twenty metres from the river. Inside, along the base of the south wall, there is a line of damp — pale brown, dead level, as though it had been ruled.
He painted it with waterproofer, two coats. The next year it came back a finger higher.
He cut a mark into the plaster and wrote the year beside it.
By the seventh mark he went down to the river to check the level. He found a stone step to measure against and compared seven years of photographs.
The river had not changed. It rises and falls within twenty centimetres and comes back to the same place every year.
He went in and measured the spacing between his seven marks. Even. A finger a year, with very little error.
He chipped away a patch of the plaster, wanting to see how far the damp had got into the brick.
The brick was dry.
The stain was in the render only, half a millimetre of it. Behind that, dry all the way — dry enough that the lime rubbed off white on his thumb like chalk.