Im sorry, but Boris wasn't a great mayor of London, he was Ok with the photo ops and blustering about bicycles, but he didn't really achieve anything apart from fronting up the Olympics, which Ken Livingstone had started anyway. He didn't do anything about air quality, abandoned the extension of the congestion zone, made congestion worse by mucking about with many key roads which are a complete mess and more dangerous, brought in a few vanity projects like the cable car,garden bridge, wanted to have an airport in the Thames estuary in a nature reserve, I could go on. Some of his chosen advisors were crooks, not his fault, but bad choices.