Stone of offence: how a concrete block became the hub of a diplomatic riot between Gibraltar and Spain

It's literally about a block of concrete. Yet this block of concrete, which was part of an artificial reef just off the coast of Gibraltar, plays a central role in rising tensions between Gibraltar and Spain this week. It risks worsening ties between Madrid and London at a critical time for the post-Brexit status of “The Rock,” the nickname for the British semi-exclave.