By the end of the 16th century Holywell was the largest town in north east Wales. Small industries had been introduced such as lead smelting but were very poisonous to the plant and animal life in the valley. Local residents complained and an angry crowd even pulled down one smelting building in 1590.
By the beginning of the 18th century a number of more successful industries were operating including three corn mills and two snuff mills. In the 1750s new industries appeared, fuelled by new technologies in smelting and working copper, zinc and other minerals mined locally. In addition, Greenfield’s proximity to the River Dee was an advantage for trading with Liverpool, a growing centre for international trade. A dock was built at Greenfield and this allowed around 40 vessels to operate from here carrying cargoes of 30-50 tonnes.
By the 1780s, copper and cotton factories dominated the many industries in the Valley. The Parys Mine Company brought copper from Anglesey to be turned into bowls and manillas for trade in West Africa. It was this company more than any other that launched Greenfield and Holywell onto the international economic stage. Wooden ships sailing and trading in tropical waters were always at risk of damage by burrowing sea worms so the hulls were covered with copper sheets. With thousands of British ships trading all over the world, copper sheets and bolts made at Greenfield were essential to the economy and brought success and growth to Holywell and the Valley. By 1800, Holywell had grown to over 5500 people and new rows of houses were built for the factory workers such as Battery Row and Tai Coed. This peak of success was not to last however and the 19th century saw more uncertain times of boom and bust.