It is extremely sad that the UK imports stone, when we have plenty ourselves. I just can't see how it can be justified on environmental grounds, because of the CO2 emissions from transporting it half way round the world, as well as the costs. It will use the same amount of energy extracting the stone in the UK as in China, and I expect that with better regulations, our machinery will produce less pollution. And, it would give employment to people in the UK.
I hear that even bulk materials such as roadstone are often imported, while the UK has vast reserves of quartz-dolerite and other suitable rocks. I have to wonder why this situation came about, and what kind of imbeciles have been running the country for at least the last 50 years.