"The Greenwich Pensioner," Charles Dibdin, 1790, Walpole Library.Greenwich Hospital provided a safety net for the sailors who kept Britain safe and flourishing. Deductions from the pay of merchant and naval sailors helped to provide for their care when they were disabled, as is this man. Dibdin created this piece (which was published by Carrington Bowles) to commemorate those sailors who gave everything for the nation, and to celebrate the way the nation cared for them.
Our pensioner claims to have sailed on the Rover, a ship that I am fairly certain was invented for this song, as a quick search hasn't turned anything up on an eighteenth century ship rigged naval vessel by that name prior to 1790.
Jack doesn't wear his slop clothes anymore, but a suit of clothes that hint at his former profession.