This report is from this week's CNBC's UK Exchange newsletter, which brings you expert insights on the most critical business stories in Britain. You can subscribe here . Hello and welcome to CNBC U.K. Exchange. This week, I take a look at the challenges faced by former Google executive Matt Brittin as he prepares to take charge at the BBC, one of the U.K's most enduring cultural exports and a crucial part of its media and communications landscape. The BBC is cherished by most Britons — and