Along the west wall of the ground floor, at about the height of a kitchen counter, the brick changes colour in a band roughly forty centimetres deep. The colour varies, with dull blue-green in patches, a long rust streak near the far door and one almost black section by the stair.
The dye troughs stood along that wall from 1912 until the mid-fifties. Wooden and refilled by hand, they splashed, and fifty years of splashing soaked into the unglazed brick for good.
During the conversion the contractor priced two options: chemical cleaning, which would have taken most of it off and left the brick patchy in a different way, or washing with water and leaving it.
The architects argued for the second and the owner agreed, on the grounds that the building had been a dye house longer than it had been anything else and that pretending otherwise would be a strange thing to spend money on.
Guests ask about it most mornings. It's the only part of the building that needs explaining, which is a good ratio for a hotel.