At the cessation of the American Revolutionary War he went on half-pay and attempted to return to Connecticut, however, hostility to the Loyalists remained strong, and after an encounter with angry Patriots, fled to England.

[1] As Provincial Secretary and Registrar his salary was supplemented by the fees collected when land patents were granted, however, half of this income was later transferred to the attorney general.

[2] A plaque for a stained-glass window honouring William Jarvis at the Cathedral Church of St. James (Toronto) states, "First Provincial Grand Master of the Ancient Order of Free and Accepted Masons".

[3] William and his wife Hannah Jarvis were slave owners who objected to Simcoe's plan to abolish slavery in Upper Canada.

One of their slaves, Henry Lewis, escaped and made his way to Schenectady, New York, where he wrote Jarvis, offering to buy his freedom.