The external repairs to the masonry were done at the same time that the steel frame was being built inside the walls, and was done from a full structural scaffold. The work principally consisted of rebuilding the tops of the walls, particular on the north east side, rebuilding the brick gable end containing the rose window, restoring the rose window itself, and rebuilding two of the four pinnacles. The masonry work was done by Stone Central.
About 50% of the stone was recovered and used where possible. Large sections of the walls were repointed in lime mortar, and there was a limited amount of stone repairs.