Downing had from the first been a champion of English mercantilism, and was therefore hostile to the Dutch as the commercial rivals of England. He had emphasised the importance of Baltic markets for English merchants to Thurloe during his first embassy, which had given him an insight into the economic policies of the Dutch government, and his intelligence network then had allowed him to discover how its traders were able to evade the Navigation Act of 1651. This knowledge enabled Downing to be instrumental in strengthening and clarifying the provisions of the earlier act in the Navigation Act of 1660.