This report is from this week's CNBC's UK Exchange newsletter. Like what you see? You can subscribe here. The term Silicon Roundabout, a label for the cluster of tech firms based around the City Road/Old Street junction north of the City of London, was first coined in 2008. It entered common parlance, though, when in November 2010 the then-new Prime Minister David Cameron placed the area at the heart of his government's growth ambitions. "Silicon Valley is the leading place in the world for