Complex sentence: Stuart Aston, managing director, said that the problem is the Bath Stone used on the more decorative areas of the cathedral, has not stood up well to the salts and sand in the maritime climate of Cornwall.
Split into simpler sentences: Stuart Aston, managing director, said that the problem is the Bath Stone used on the more decorative areas of the cathedral. It has not stood up well to the salts and sand in the maritime climate of Cornwall.