(1814-1882), electrical engineer and manufacturer

William Thomas Henley, born in Midhurst, Sussex, but moved to London in 1830 aged 16, working as a labourer in the docks. In his spare time he taught himself instrument making. About 1837 J. P. Gassiot, a keen amateur scientist, and one of Henley's early customers, recommended him to Professor Wheatstone of King's College, for whom he made telegraph equipment and electric motors. Henley found that cheap insulated wire was not readily available for making electromagnets, so he developed a wire-covering machine that insulated six wires in cotton or silk simultaneously. By 1839 he was supplying insulated wire in quantity to other instrument makers and experimentalists at about half the price of his rivals, and he used the profits to strengthen his business and to fund electrical experiments.

The Electric Telegraph Company acquired the Cooke and Wheatstone telegraph patents in 1846 and placed significant manufacturing orders with Henley, but failed to pay him. Henley responded by inventing an improved telegraph, in which pulses of electric current were produced by a combination of moving coils and permanent magnets, rather than from batteries (patent no. 12236, 1848). He won a gold medal for his equipment at the 1851 Great Exhibition. In 1852, he sold his patent rights to the English and Irish Magnetic Telegraph Company for £68,000.

Henley set up as submarine cablemaker in Greenwich in 1857, and moved to a new factory in north Woolwich in 1859. Here he manufactured the Persian Gulf cable 1651 miles long, which was the first submarine cable to be exhaustively tested during manufacture, transport, and laying. This success enabled him to win the contract for the armoured shore sections of the successful 1865 and 1866 Atlantic cables.

In 1876 a limited company was formed to carry on work under the title of W. T. Henley & Co. Ltd. When this was wound up, most of the works became the property of the Telegraph Maintenance and Construction Company, who then closed it. A small portion of the works was formed into W. T. Henley's Telegraph Works Company (Limited) in 1880, of which Henley was a director.

Henley died on the 13th of December 1882 at the age of sixty-nine, his company continued making submarine cables until the turn of the century.