Bruce was a merchant in Rotterdam during the 1650s, and played a role in the Restoration of Charles II in 1659. He carried messages between the exiled king and General Monck, and his loyalty to the king was rewarded with lucrative official appointments, including that of Surveyor General of the King's Works in Scotland, effectively making Bruce the "king's architect". His patrons included John Maitland, 1st Duke of Lauderdale, the most powerful man in Scotland at that time, and Bruce rose to become a member of Parliament, and briefly sat on the Scottish Privy Council.