Canterbury Cathedral is falling apart at the seams, with chunks of masonry dropping off its walls and a fifth of its internal marble pillars held together by duct tape.  An art student paints in the cloisters, but trustees say parts of the building may have to be closed to visitors for safety reasons The extent of the building's disrepair was revealed yesterday at the launch of a global campaign to raise £50 million over five years for urgent and long-term renovation and conservation.The cathedral, the mother church of worldwide Anglicanism which was founded in 597 by St Augustine,...