The heritage also provides exceptional testimony to the way in which a historic territory that was once dominated by agricultural production underwent a transition to become a territory dominated by a new order: industry. The collieries themselves, the slag heaps and the miners’ houses are all evidence of this sudden change from a rural civilisation to an industrial one, bearing witness at the same time to the formation of the working class during the nineteenth and twentieth centuries, with its trade unions, strikes, friendly societies, healthcare provision and a fundamental right to work.