You'll remember how, in his early "Vote blue, go green" days, David Cameron was rather embarrassed when it emerged that he cycles to work -- but has his car follow behind with his suit and briefcase.

Perhaps in an attempt to atone for his environmental sins, Cameron announced a ban on ministerial cars in all but the most exceptional circumstances.

But today's Guardian reports that the move has hit something of a roadblock. While ministers are now obliged to take the train, their red boxes, for security reasons, must travel separately in a private car.

To compound the confusion, the same ministers are prohibited from accompanying their red boxes in the car in order to work.

There is something wonderfully English and absurdist about a minister struggling against the vagaries of the train timetables (and even the dreaded rail replacement bus) while his red box enjoys a smooth ride in a Jag.

But before he lets his ministers loose on the trains, Cameron might like to remember the unfortunate experience of his director of strategy, Steve Hilton, who felt the long arm of the law after an expletive-fuelled row with rail staff.

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