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of Seaham Harbour
1819 The Londonderry family became coal owners through the marriage in 1819 of the third Marquess of Londonderry with Lady Frances Anne Vane-Tempest, a descendant of the Vanes of Longnewton and the Tempests of Wynyard. The Tempest family owned a number of collieries around the city of Durham.
Under the third Marquess and his wife, these collieries were developed.
1821 The Seaham estate was purchased; Lord Londonderry laid down a railway from Rainton to Seaham, with branches to all the collieries in which he was interested, and constructed a dock at Seaham.
1899 The company was registered on 31 May, to acquire various collieries in the County of Durham. 
c.1927 A new pit was being sunk.