I found several of these old bricks when turning over a section of garden many years ago.  This old brick has its links with the 3rd Marquess of Londonderry, who owned coal mines, the harbour at Seaham and coalmines throughout the region. Most of the bricks I found carried the name 'Londonderry'.


Extra:  Lord Lambton also had interests in mining in the NE and bricks produced for the Lambton Collieries (1783 onwards) and other customers are common around here.