Short answers, pulled from the story.
Joseph Clement (the 13th of June 1779 - the 28th of February 1844) was a British engineer and industrialist from Great Asby in Westmorland. He is chiefly remembered as the craftsman who built Charles Babbage's first difference engine between 1824 and 1833.
Babbage employed Clement in 1823 to design and construct the mechanical components of his difference engine. Clement's precision machine tools and engineering skill made him the principal maker of the project, which ran from 1824 to 1833 but was never completed.
The Society for the Encouragement of Arts awarded Clement its gold medal in 1818 for a machine to mark ellipses. In 1827 he received the Society's gold Isis medal for an improved lathe of unprecedented precision, and the following year he received their silver medal for his self-adjusting centre chuck.
In 1828, Clement began promoting a standardised system of screw threads and started producing fluted screw-cutting taps and dies. Joseph Whitworth was one of Clement's journeymen at that time and later carried the standardisation work forward; the Whitworth thread became a standard for machine screws.
Clement worked for Alexander Galloway in Holborn, then moved to Joseph Bramah at Pimlico, where he was appointed chief draughtsman and superintendent under a formal agreement dated the 1st of April 1814. After Bramah's death he became chief draughtsman at Maudslay, Sons and Field in Lambeth before opening his own workshop at 21 Prospect Place, Newington in 1817.
Clement built his great planer some years after his first planer of 1820. It could handle work six feet square and was capable of planing circular, spiral, and conical surfaces as well as flat work. For more than ten years it was the only machine of its size, running night and day; a full description appeared in the Transactions of the Society of Arts in 1832.