John Wilkinson was born c1728 in Clifton, Cumberland. He became known as "Iron-Mad Wilkinson". He was the son of Isaac Wilkinson, a farmer and iron worker. The family later moved to Backbarrow, near Lake Windermere and ran a furnace the there. John was educated at the Dissenting Academy in Kendal and about 1748, John found employment in the ironworks of Midlands.
The family purchased the Bersham Ironworks from the Lloyd family in 1753 and lived at Plas Grono, Erddig. The ironworks had been worked by coal with poor results but Abraham Darby of Ironbridge perfected the use of coal over charcoal and this was subsequently used at Bersham. In 1762 John and his brother William took over the ailing ironworks and turned it into a highly profitable business. In 1774, he took out a patent for the boring of cannon and is said to have supplied cannon for both sides in the American War of Independence. He also produced most of the cylinders for the famous Boulton and Watt steam engines. He was a shareholder in the Ellesmere Canal and reopened the Minera lead mines and others near Mold.
In 1792 he bought the Brymbo Estate where he set up blast furnaces. He served as High Sheriff of Denbighshire in 1799. He died at Brymbo Hall on 14th July 1808 but is buried in Cumbria in an iron coffin. He was brother-in-law to the scientist Joseph Priestley His estate was disputed when he died and much of his fortune went in litigation between his nephew Thomas Jones and his mistress and 4 children. The Bersham works were derelict within 20 years. The Brymbo works were bought out of Chancery in 1841 and a new limited company was formed.