Construction of Puffing Billy began in 1813. William Hedley developed the locomotive for Christopher Blackett’s Wylam Colliery in Northumberland, working with enginewright Jonathan Forster and blacksmith Timothy Hackworth.
The machine was built to replace horses hauling coal wagons along the colliery railway. Its designers were testing whether ordinary wheel-to-rail adhesion could provide enough traction, rather than relying on a rack, cable or other special system. That experiment helped establish a practical direction for later steam locomotives.
Puffing Billy was not completed in a single, unchanging form: it was constructed during 1813–1814 and later rebuilt. The locomotive initially used multiple wheels to spread its weight over weak cast-iron rails. It was later given ten wheels, then returned to a simpler arrangement when stronger edge rails became available. It remained in colliery service until 1862 and is now preserved at London’s Science Museum, making it the world’s oldest surviving steam locomotive.