W. H. Harling founded the firm in 1851 at 47 Finsbury Pavement, London. They specialised in making drawing instruments, with a factory at Grosvenor Works, Hackney, London EC. According to Scott-Scott they ceased making instruments to the traditional pattern in 1929 and changed to flat pattern ones. In 1964, having merged with Blundell Rules Ltd to form Blundell Harling, they moved to the Blundell premises in Weymouth.