It wasn't long ago that an aspiring Deputy Prime Minister might have  a Jag for work and a spare in the garage. But the tide is turning.

Despite Gordon Brown's promise to swap his government Vauxhall for a hybrid - a Toyota Prius - he understandably balked when push came to shove, and opted for a V8 Jaguar XJ instead.

But the new breed of cabinet minister has definitely taken the petrol-electric route. According to this article in the Guardian,  James Purnell, Douglas Alexander, Ed Miliband, Hilary Benn (unsurprisingly for an environment secretary), Hazel Blears and John Denham all drive hybrid Toyotas or Hondas.

It's probably just as well, because the prime ministerial Jag is no ordinary 35mpg XJD, it's a 2.7-tonne armoured XJ. I've never driven one of these, so it's difficult to get any real economy figures, but Richmond-based Carty Associates, which provides a secure limo and driver service, reckon that an armoured XJ will do around 12mpg in town.

Oh yes, and it also has to be driven to the other end of the line for all those publicity-coup train journeys - that's not really saving fuel.

So when you're next getting stressed about reducing your carbon footprint remember that, unless you're commuting in a Bugatti Royale, things could be worse.