1935. Quarry Hill Flats were constructed using the Mopin system, first used in France. Prefabricated pressed steel formed the skeleton with concrete blocks which were made on site. This was a cheap building method as it removed the need for skilled labour and more expensive brickwork. It was to prove defective, water seepage led to rust, which weakened the whole structure of the buildings. To repair would have been more costly than rebuilding. This is a diagram of the factory, set up to make the concrete blocks on site.