 Although Downing was unable to realise Cromwell's plans during his first period in the Netherlands, he gained insight into the Dutch republic's system of public finance, which he first applied to the royal finances the early Restoration period of 1660 to 1665, allowing them to be reformed in imitation of Dutch practice.Downing showed himself to have been an able diplomat for the Protectorate, and was maintained in his post during the interregnum subsequent to the fall of Richard Cromwell.He was thus enabled in April 1660 to make his peace with Charles II, to whom he made himself useful by communicating Thurloe's despatches, and declared his abandonment of "principles sucked in" in New England of which he now "saw the error".