Early in the 18th century, John Hylton (died 1712), the second son of Henry Hylton, "de jure" 16th Baron Hylton, gutted the interior to form a three-storeyed block (one room on each floor). He also inserted large, alternating, pedimented sash windows in the Italianate style and added a three-storeyed north wing to the castle (as seen in Bucks' engraving of 1728). A doorway to the new wing was added and approached by a semi-circular staircase. Above the doorway was a coat of arms, believed to be the one created to commemorate the marriage between John Hylton and his wife, Dorothy Musgrave. It is now located above the doorway to "The Golden Lion Inn" at South Hylton, on the opposite side of the River Wear.