'The most important mechanical inventor of the nineteenth century'.

Roberts worked for Maudslay in 1814 for a couple of years as a turner and fitter, learning the importance of accurate machine tools where hand-work was replaced by mechanisms. He set up in Manchester as a designer and manufacturer of textile machinery. His most famous invention was making the spinning mule, invented by Samuel Crompton in 1779. Self-acting, it mechanised the actions formerly done by hand.

Roberts was also a locomotive engineer and maker of shipbuilding equipment. In 1847 he patented a novel punching machine to complete the first tube for the Conwy tubular railway bridge in North Wales.