Blackett played a crucial role in the development of some of the earliest steam railway locomotives to be built anywhere in the world.
A member of a family which had owned the mining interests in Wylam, Northumberland, for much of the eighteenth century. he assumed control of the business in 1801 and took a great interest in improving the efficiency of the horse-powered five-mile waggonway by which the coal was moved to the offloading point on the River Tyne. He had the wooden rails replaced by an iron plate-way in 1808, after which the horses could haul two loaded chaldrons (waggons) rather than the single chaldron they could manage previously.
Blackett also encouraged William Hedley, his mine engineer, to experiment with steam traction, and over the period 1813 to 1816 horses were replaced by steam locomotives designed by Hedley. Two of these locomotives survive in preservation, much rebuilt, as Puffing Billy and Wylam Dilly.
Blackett remained in charge of Wylam Colliery until his death in 1829. His descendants remained Squires of Wylam until as recently as 1971.