He was christened Thomas Clark Iliff in 1773 at St Andrew, Holborn, the son of Thomas and Ann of Portpool Lane.
He married Harriot Sophia Potter at St James, Clerkenwell in 1796; both were from that parish.
He was assessed to Land Tax on property in Robert Street in 1800 and Mount Pleasant in 1812.
He is listed in the book Watchmakers and Clockmakers of the World in connection with watches manufactured 1802-8.
The christening records at St James, Clerkenwell of a son George in 1813 and a daughter Agnes Martha in 1816 show their address as George’s Court and their father as a watch maker.
In 1814 he entered a mark at Goldsmiths Hall in partnership with John Weston as watch pendant makers from 47 Ironmonger Row and in the same year a mark alone from the same address in the same capacity. 47 Ironmonger Row had become the address of watch case maker Matthew Govett (Grimwade p.313, 345) in 1813.
Changes of address were notified to Goldsmiths Hall in 1815 to Mount Pleasant, Gray’s Inn Road, in 1822 to 55 Rosoman Street, Clerkenwell, later to 22 Yardley Street, Clerkenwell, in 1824 to Whiskin Street, Clerkenwell and in 1826 to 21 Rosoman Street..
His burial in 1837, late of 52 Whiskin Street, was recorded at New Bunhill Fields Burial Ground.