The somewhat ironically-named Greenfield Valley was the site of a remarkable concentration of heavy industrial sites, using water power provided by the Holywell Stream, and stretched from Holywell Town some 2km to Greenfield Harbour on the River Dee. The narrow and steep-sided valley was the home to no fewer than nine major water-powered installations and numerous mills, factories and works which, from 1755 onward, produced or processed copper and brass wire and sheet, cement, dyes, wool (flannel), corn, paper, cotton, snuff, red lead and various chemicals. The peak of industrial prosperity was around 1800. The main line of the Chester and Holyhead Railway later crossed the coastal plain to the south of the harbour and a branch line was built up the valley (most steeply-graded conventional standard gauge railway in the UK) to serve the industries, Holywell Town and the lead mines and quarries beyond. Industrial activity since declined and most factories had closed by the 1960s, however there is much of interest still to be seen and the former major importance of the valley is recognised by the establishment of the Greenfield Valley Heritage Park.
B.A.Malaws, RCAHMW, 05 October 2010.