Have you ever wondered about these paviours?
They skirt the northern and western sides of the inner footway outside Drummond Place Garden, and many examples have a peculiar blue-ish hue. The words read:
TEES SCORIA BRICK CO.
One Joseph Wharton of Darlington patented a machine for making bricks, tiles, &c. from molten blast furnace slag (scoria) in 1877. They had the advantage of being tough, waterproof, and resistant to chemicals.