Job Isles was born in 1842 at Farsley, between Leeds and Bradford, the son of a cloth weaver and initially followed in his father’s footsteps. In the early 1860s he had left the woollen trade and taken up employment as an office clerk with Thomas Smith, crane manufacturers at nearby Rodley. He married in 1865 and some four years later, with a partner called Thomas Whitham, they established a mechanical engineering business - trading as Isles & Whitham at Prospect Works, Robin Lane, Pudsey, making steam cranes and lifting machinery.
