The Isle of Purbeck is a kingdom of its own. The villages around Swanage, like Langton and Worth Matravers, are full of quarry-men’s cottages, all built of the same dove-grey Purbeck stone. They look as though they have grown from the landscape. Swanage, on the other hand, doesn’t fit in at all. In 1935 the artist Paul Nash was appalled by its “development” in what he described as “perhaps the most beautiful natural site on the South Coast”, lying between two great ridges of chalk downland. But to me, Swanage is a remarkable, quirky and often fine-looking place, and quarrying was always at its heart….