Bruce's early work involved advising clients and rebuilding existing houses, rather than designing new buildings from scratch. Panmure House and Leslie House (seat of the Earl of Rothes) had been projects of the king's master mason John Mylne. At Panmure, although Bruce has been credited with the design in the past, the works were overseen by Alexander Nisbet, although Bruce did design the gates and gate piers. At Leslie, Bruce oversaw the works after Mylne's death, and probably made his own amendments. Panmure was demolished in the 1950s, and only a small part of Leslie House remains standing, following a fire in the 18th century. Bruce later advised the Duke of Queensberry regarding his plans for Drumlanrig Castle.