The Bedlington ironworks originally consisted of two elements – a mill in Bebside and a furnace at Bedlington Mill A lease of 50 acres (20 ha) on the Bebside side of the river was taken in 1736 by William Thomlinson, an established ironmaster from Skinnerburn in Newcastle upon Tyne, though he died in 1737 before the works was properly established.

By 1757, when it was sold again, there was a slitting mill which employed 40 nailers, a quay on the Bedlington side of the river and a "commodious dwelling house, fit for a gentleman's family consisting of ten fine rooms, four of which are hung with genteel papers, with good cellars, a stable, large garden and other conveniences".

The ancient corn mill at Bedlington was taken over in 1759 by Malings & Co of Sunderland, who built a blast furnace for foundry work.

Longridge, influenced by a report from Robert Stevenson of Edinburgh, decided on malleable iron rails and his agent John Birkinshaw developed a number of wedge-formed shapes to reduce the amount of iron, taking out a patent in 1820, and the rails were made with a swell or curvature in the middle.

The 2-mile (3 km) wagonway (which cost 15 shillings a yard or 16 shillings 4¾ pence a metre) was a great success and deeply impressed George Stephenson, a close friend of Longridge who went on to use Birkinshaw's invention in the Stockton and Darlington Railway and by 1822 the Bedlington Iron Company had delivered 1,200 long tons (1,200 t) of malleable iron rails to the venture.