So it looks like the £25 a day congestion charge for gas guzzlers will never see the light of day.

According to Mayor Boris' press office a final decision has not yet been made, but our blonde bombshell of a new mayor made the eradication of the new charge a manifesto commitment and considering he is on record as describing the proposed levy as "the most vicious fines [sic] of any civilisation yet known" he will be left looking even more stupid than usual if he does not scrap the proposed changes.

Attempts to characterise the new mayor as anti-green have always been overly-simplistic. In his inimitable style, Johnson once described himself as "a voortrekker of the Cameron movement", who breathes "the spirit of the solar-powered, bike-riding, glacier-friendly modernising tendency of which I am proud to be a part". He is also a famously keen cyclist and his manifesto included eye catching commitments to plant 10,000 trees across the capital and introduce a token-based scheme to promote recycling.

Furthermore, there is little doubt that mistakes were made by his predecessor in the development of the £25 a day charge. For example, the debate over whether or not the charge would actually cut emissions was never comprehensively won and there were valid concerns that the decision to exempt smaller cars from the charge would have undermined demand for genuine zero emission electric vehicles.

Furthermore, the arbitrary nature of the £25 charge, bearing as it does no relation to vehicle emission levels, meant it was far too easy to characterise the move as a classic example of the politics of envy, a relic from Mayor Ken's days as a Class Warrior designed solely to penalise the wealthy residents of Chelsea. The whole exercise would have been far easier to defend as a genuine environmental initiative if a sliding scale of charges had been introduced whereby cars with emissions of 120g per km pay £8, while those cars emitting double pay double.

And yet despite these flaws, it is hard to regard the decision to scrap the £25 a day charge as anything other than a retrograde step.

Imperfect it may have been, but what the new charge had in spades was symbolic value – and you can't overestimate the power of symbolism.

Combined with changes to road tax bands designed to make it more expensive to run high emission vehicles the new charge would have sent out a clear signal to consumers and businesses that gas guzzling cars are not in the social interest. Such signals would undoubtedly be ignored by many of those who voted for Boris, but the combination of higher costs and a nagging sense that they were somehow in the wrong would also serve to steer some towards more environmentally responsible choices.

Instead, one of the most powerful politicians in the UK is now poised to send out the contradictory signal that high emission vehicles are in fact fine and despite their disproportionate contribution to climate change they should not be penalised.

Moreover, just as the government's fudging of environmental targets, refusal to countenance hypothecated green taxes and failure to invest adequately in climate change adaptation has undermined the credibility of many of its green policies, the decision to effectively water down the congestion charge will overshadow any future environmental initiatives Boris comes up with.

It is not too late to hope for a u-turn, but something tells me that Boris, like his hero, is not for turning.

Right, I'm off to stock up on canned food and start work on a nuclear bunker in the back garden.

Have a good weekend,

James