In 1707, Abraham Darby I patented a method of making cast iron pots.  His pots were thinner and hence cheaper than those of his rivals.   Needing a larger supply of pig iron he leased the blast furnace at Coalbrookdale in 1709.  There, he made iron using coke, thus establishing the first successful business in Europe to do so.  His products were all of cast iron, though his immediate successors attempted (with little commercial success) to fine this to bar iron.
Bar iron thus continued normally to be made with charcoal pig iron until the mid-1750s.  In 1755 Abraham Darby II (with partners) opened a new coke-using furnace at Horsehay in Shropshire, and this was followed by others.  These supplied coke pig iron to finery forges of the traditional kind for the production of bar iron.  The reason for the delay remains controversial.