Hem Heath colliery (1924-1950). The Duke of Sutherland cut the first sod in July 1924 for this comparatively new pit. Ventilation was a problem and it became difficult to increase output. After nationalised in 1947, it became obvious that the existing shaft arrangements were inadequate if the rich resource were to be fully exploited, so work began in 1950 to restructure the pit to make a virtually new colliery. During modernisation production never stopped.