He claims to want a greener and safer London, but a Boris Johnson mayoralty would lead to hundreds more pedestrian casualties every year.
Figures from Transport for London show that Ken Livingstone's rephasing of traffic lights has in fact led to a reduction of casualties by almost a third.
Similarly they suggest that extending 20 mph zones would cut deaths and serious accidents by a further 40 per cent.
Yet despite these figures, Boris Johnson would make it harder for pedestrians to safely cross the road and will oppose any increase in 20 mph zones.
Speaking after Boris announced his opposition to reduced speed limits, the Mayor said:
"By making road safety measures such as more pedestrian crossings and longer green man phases a much higher priority over 500 fewer children are killed or seriously injured on London's roads each year than when I was first elected in 2000. But we have to continue to move forwards to reduce road deaths. The fundamental cause of road deaths is the speed of traffic."
In fact new figures from the United Nations show that road accidents now kill as many people worldwide as Aids. These deaths are indiscriminate, but disproportionately affect the poorest and the youngest members of society.
Yet despite this rise in road accidents worldwide, Ken Livingstone has presided over a significant reduction in deaths and serious injuries on London streets. A Boris Johnson administration would bring that trend to a dramatic halt.
For his own part Boris Johnson has constantly piped out the statistic that 27 teenagers died as a result of stabbings and shootings last year. And he now poses as the man who would make our children safe. Yet when he was confronted with figures showing he would actually increase the number of child deaths, he brazenly accused the mayor of playing politics with peoples lives.
But it is now becoming clear that it is Boris' anti-pedestrian, pro-car politics that is the real danger at these elections.
Because despite all of his claims to want a safer London, Boris Johnson's policies would increase the greatest cause of deaths on London's streets. And just as he sees stealing kids bus passes as a bigger priority than setting up youth projects, so too does he prefer to please motorists than to save lives.
So no matter how well he hides his smirk in this campaign, there will be very little to smile about if he wins in May.