"I'm afraid that Hillary Clinton suffers from pseudologia fantastica," said my friend the psychiatrist. The would-be president of the United States is not one of his patients: this is what might be described as an informal diagnosis, provoked by Mrs Clinton's extraordinary claim to have dodged sniper-fire in Bosnia in the service of her country.

She made the remarks in a speech at George Washington University - that's George Washington as in "I cannot tell a lie, father".

The speech was to an audience chock-full of generals and admirals - and Mrs Clinton was clearly determined to demonstrate that she was up to being their commander-in-chief: "There was a saying around the White House that if a place ... was too dangerous, the President couldn't go, so send the First Lady instead. So that's where we went. I remember landing under sniper-fire. There was supposed to be some kind of greeting ceremony at the airport but instead we just ran with our heads down to get into the vehicles to get to our base."

When reporters and others who accompanied Mrs Clinton on that 1996 trip protested that nothing of the sort happened, she grimly stuck to her tale: "We had to be moved inside because of sniper fire. There was no greeting ceremony. Now, that is what happened."

Unfortunately for Mrs Clinton, after a few days of her increasingly irate dissembling, CBS started broadcasting its 12-year-old tapes of the then First Lady landing at Tuzla airport.

It showed the following : No sniper fire. No running for cover - heads down or otherwise. Instead we see Mrs Clinton - accompanied by daughter Chelsea - taking part in a charming greeting ceremony, receiving a bunch of flowers from an eight-year-old girl. Just for the record, husband Bill had flown in to Tuzla some months earlier (minus Hillary) when it actually was a bit "dangerous".

Faced with this avalanche of incontrovertible facts, Mrs Clinton finally collapsed into teenagerish incoherence: "You know, I think that a minor blip, you know, if I said something that, you know, I say a lot of things - millions of words a day - so if I misspoke, that was just a misstatement." Yes, dear.

Alas for her long-suffering supporters, Hillary Clinton has form: this is by no means an isolated incident.