For many, the golden haired Mayor of London, Boris Johnson, is almost a cartoon character. He's made his mark through the "Boris" brand - an unconventional, dishevelled, funny politician, who admits his mistakes and entertains at the same time. This week, reporter Philip Williams spends time with the irrepressible Mayor, as he campaigns for a seat in parliament. But is this just the first step in his lifelong ambition, to become the Prime Minister of the UK?