Boris Johnson, the London Mayor, has apparently sent American President Barack Obama a £10 congestion charge bill because he was driven around the city in his armoured limo, called "The Beast", when the roads had not been closed.
The Pope was not charged when he visited London in September because the roads were closed when the Popemobile rolled through, says the mayor.
America is said to owe London £5.2 million worth of unpaid congestion charges for driving embassy cars in central London. The US Embassy says it is exempt from paying "direct taxes", but the mayor says the charge is not a tax.
Several other embassies refuse to pay the £10-a-day charge. America, Russia and Japan are top of the list of non-payers, with the total bill standing at £51 million.