Henry Liddell, Esq., c. 1673-1717. Younger son of the Liddells of Ravensworth. Became the supervisor of the family's extensive interests in the Durham coalfield and thereby one of the leading figures in the coal-trade. William Cotesworth of Gateshead, c. 1668-1725. Rising local entrepreneur. Shared business and political interests produced a mutual understanding and trust between these two men of different social backgrounds. The friendship lasted until Henry Liddell's death and had implications for some time afterwards. The letters provide 'a vivid picture of the labyrinthine workings of the Newcastle coal-trade at a difficult time in its history.' Market: Economic history, 19c.