In 1801, when his partnership with John Smith was dissolved, William Cooley was described as a cutler.  He apparently never served an apprenticeship, however, and his biographical details are sparse.  He was not listed in the 1797 directory.  It is known, however, that Cooley became a supplier of tables knives and forks to the American market.  He seems to have allied himself with other merchant-manufacturers to exploit this market.  Until it was dissolved in 1807, Cooley was linked with the partners of Naylor & Sanderson: namely, George Naylor, Thomas Sanderson, and Daniel Brammall.  Cooley’s business was hit hard by the Orders in Council (1807), which blockaded trade with American and Continental ports.  In evidence presented to a Parliamentary Committee in 1811, Cooley was described as a maker who had been for ‘many years in the habit of manufacturing to a very large amount for the export trade to the United States’.  But towards the end of 1811

he was obliged to turn off a considerable number of his hands; that after Christmas, finding the trade with the United States did not open, he was compelled to turn off more of his hands, and that he now pays a sixth part of those wages which he pays when the export to the United States is open … [and] … that for the last fifteen months, one-half of the amount he manufactured he was obliged to lay to his stock, and that the few hands he retained, were limited to, on average, about one-half work, or three days work in each week (House of Commons: Minutes of Evidence Taken Before the Committee of the Whole House, Relating to the Orders in Council, 1812).

In a Sheffield directory in 1811, William Cooley was listed as a table knife manufacturer at 3 Sycamore Street.  But in the next directory (1816), his name did not appear.  His subsequent career is so far untraced.