While at sea, Vassa missed London. He returned to the city in March 1767 and became apprenticed to a hairdresser in Coventry Court, Haymarket. He trained from September 1767 to February 1768. At the same time, he also took lessons in French horn blowing and in arithmetic. In 1768, he began working as a hairdresser for Dr Charles Irving, a scientist, and was paid $£ 12$ per annum, a sum that was not sufficient for him to live on. He also worked as Dr Irving's assistant. Dr Irving had developed a method for converting sea water into fresh water. In May 1768, Vassa, in order to make more money and to satisfy his peripatetic itch, went to work as a hairdresser on board a ship sailing to Italy and Turkey. He returned in 1770 and hired himself out again in April 1771, as a steward on board another ship headed for the West Indies. Vassa hired himself out again on his return as a steward on a ship headed to Nevis and Jamaica in December 1771. In August 1772, he returned and went to work again for Dr Irving until May 1773. Unable to keep away from the lure of the sea, in 1773, he joined the expedition to the North Pole under the command of Constantine John Phipps. He returned after four months and, in the spring of 1774 , sought employment again as a steward on board a ship. Vassa also recommended an acquaintance, John Annis, as cook. When Annis' former owner kidnapped him from the ship, Vassa came into contact with the English abolitionist, Granville Sharp, whom he hoped would help him to free Annis. Their attempt was unsuccessful, but Vassa was now in touch with one of the most important abolitionists of the day. In 1775, Vassa was employed by Dr Irving to work as an overseer on his new plantation colony on the Mosquito Coast of Central America. Vassa remained in this position until June 1776, when he felt the urge to return to London. After Vassa left Dr Irving's employ, Irving hired a white overseer whose cruelty caused the slaves to attempt an escape; an attempt which ended in all of them drowning.