It’s been another bruising week in the London mayoral election campaign. Eccentric Tory contender Boris Johnson may have had the best of it. On Tuesday Ken Livingstone announced that drivers of gas-guzzlers will be charged £25 to enter the Congestion Zone from October – assuming he’s re-elected. The Greens support the move, but the Lib Dems’ Brian Paddick – he’s the gay, “cannabis cop” from Brixton, you’ll recall – was critical, notably of the same......