Is the Atlantic the only thing that divides the UK and US? As President Bush visits Tony Blair he may discover subtle but important differences between our two nations' diplomatic language.

Language doesn't appear to be President Bush's strongest suit. His struggle to find the right words of regret during the China spy plane crisis are credited with prolonging the stand-off.

The Texan's boasts of his bilingual abilities were bruised on his last European visit, when his grasp of Español failed to prevent him mispronouncing the name of the Spanish premier Jose Maria Aznar.

But in a land which shares his mother tongue, surely the President should find a firmer linguistic footing?

George Bernard Shaw's observation that the US and the UK are "two nations divided by a common language" is perhaps more accurate than many Britons might suspect.

All Grecian to me

Broaching such delicate subjects as the Kyoto treaty, the "son of star wars", or the "European army" could leave Mr Bush with the nagging doubt the British are replying to him in Grecian.

The gulf between American and British English is more pronounced than a mere difference of pronunciations, says Professor Larry Selinker, an American linguistics expert at London's Birkbeck College.

"We don't have the same language. We use the same words, but they are often used in different ways. You say one thing, but we mean another."

Take the word "scheme", for example. On both sides of the Atlantic, "to scheme" suggests nefarious plotting. However, Britons would have no moral objections to going along with "a scheme", while law-abiding Americans would still be horrified by the word's shady connotations.

Despite this, when President Bush and Prime Minister Tony Blair sit down they are unlikely to seek the aid of interpreters to unpick the nuances of each others words. This may put the American at a disadvantage.

The reach of US popular culture has given the average Briton a handle on the accents and vagaries of American English. Professor Selinker points out that when Hollywood "talkies" first hit the UK, cinema goers had no idea what the actors were saying.

You ain't heard nothing yet

Anne Robinson's Weakest Link efforts notwithstanding, the flow of British culture to the US has been modest in comparison.

"Blair will have to modify his language to be understood," says Professor Selinker.

Peter Jay, former British ambassador to the US, says such linguistic differences shouldn't be overstated.

"There occasionally may be misunderstandings, but that is also true of any two human beings."

But for a foreigner to fathom the subtlities of British English can take a lifetime. And it is not just slang and colloquialisms which differ between English-speaking nations, formal language also has its pitfalls.

Professor Selinker says he was initially at a loss to understand why the agendas for meetings began with apologies: "What did I have to apologise for?"

To "table" a motion in a British boardroom will see it discussed. In America, "tabling" something will see it put firmly on the back burner.

While "slating" someone in America refers to them being favourably nominated for office, to receive a "slating" in the UK is to be on the business end of a severe scolding.

Arguably, if you think the differences between Washington and Whitehall are merely cosmetic, then (to quote President Bush) you're "underestimating".