In 1655 he was formally appointed as the Massachusetts colony's agent in England. It is unclear, given the overlap with his governance in Acadia, when he actually went to England, but he served in this capacity until 1662. During the 1650s when Cromwell was Lord Protector the colony benefited from the relationship he had cultivated with Cromwell during the civil war. In particular, Cromwell took no steps to enforce the 1651 Navigation Act against the colony's merchants, and also overlooked complaints about the colony's repressive tactics against religious nonconformists. The latter occurred despite Leverett's personal opposition to the colony's extreme stance on religion. A common claim that Leverett was knighted by Charles II lacks a solid foundation in the documentary record.