HMS Pegasus was a 28 gun, Enterprise-class Sixth rate Frigate. Laid down in 1779 at Deptford and sold in 1816. When Hornblower stood for his examination for Lieutenant, he discovered that one of the members of the Board of Examination was Captain Charles Hammond, who was Lieutenant aboard Pegasus sometime in the past. One of the other examinees had lost Hammond's pet poodle overside in Pegasus' cutter in Port-o'-Spain.
HMS Pegasus in Wikipedia.