The HMS Worcester is Jack Aubrey's ship in The Ionian Mission. She is one of the so-called "Forty Thieves," a class of forty 74-gun third-rate ships of the line that were notorious for being poorly constructed. The shipyards that constructed them were corrupt, and would steal materials from the ship and sell them. For example, cutting copper bolts in half, using one half, and selling the other. This made a lot of money for the shipyards but severely weakened the ships themselves. The "Forty Thieves" were real, but the name Worcester was never used.