There were two piano makers named Robert Wornum, Senior (1742-1816) and Junior (1780-1852). Robert Wornum Sr. was a music seller and instrument maker, with a shop located on Glasshouse Street, London until 1777 when he moved to Wigmore Street. His son Robert Wornum Jr. began as a partner with another piano maker, George Wilkinson, in 1810. Robert Wornum Jr. started his own workshop in 1813 but took over his father’s business upon his father’s death in 1815. Wornum Jr. patented several important designs during his life, first the upright piano action in 1826 and then the tape-check action in the 1830s. His upright piano action became the foundation for all future upright piano developments. Wornum Jr. also invented both the diagonally and vertically strung upright piano. His developments did not become widely accepted until later in after his death in 1852. In 1852, the firm fell into the hands of his son, Alfred Nicholson Wornum, where he continued developing upright pianos until his own death around 1900.
Clinkscale, M., 2006. Makers of the piano, 1700-1820. 1st ed. Oxford: Oxford University Press, p.326
Palmieri, R. and Palmieri, M., 2003. Encyclopedia of Keyboard Instruments. 2nd ed. New York: Routledge, p.455-456.