A West Country surgeon, Jenner discovered vaccination against smallpox after testing the country lore that dairymaids, exposed to the mild cowpox virus, did not contract the killer disease. He published his findings in 1798, but it took ten years for the government to accept his discovery. Jenner campaigned vigorously, even encouraging the fashionable 'cowherd' poet Robert Bloomfield to write Good Tidings; or, News From the Farm (1804) to promote vaccination. By 1853 vaccination was compulsory in Britain and Jenner was posthumously considered a national hero.
The background of this painting was not finished until after Jenner's death in 1823 when Northcote wrote: 'on a table in the picture I have introduced the bones and joints of a Cows hoof and in a glass case the Cows hoof injected, all which is to show what were his peculiar Studies'.