An Israeli man forgot he was carrying a loaded pistol in his hand luggage when he flew into Britain for a holiday, a court has heard.
Benjamin Lehman, 48, from the West Bank, managed to pass security checks at Tel Aviv and Heathrow without the weapon being discovered.
But he was eventually caught when he returned to Heathrow for a flight to New York a few days later.
Lehman denies two counts of "having a dangerous article at an aerodrome."
London's Isleworth Crown Court heard that the 9mm Steyr M9 pistol, which contained 10 rounds of ammunition, was found in one of the pockets as it passed through an X-ray machine on June 17, 2004.
Lehman told police that in the rush to pack he simply forgot he still had the loaded weapon with him.
"He said words to the effect 'I forgot it was there'," prosecutor Mark Kimsey, told the court.
"But even if you did accept that he initially forgot it was in his bag, is it conceivable at all that during the three days in this country whilst using other items in the bag that he would have been unaware it was still there?" he asked.
The prosecutor said that when Lehman was interviewed, he said that he lived in a "particularly dangerous part of Israel" and he had a licence for the pistol.
But, the barrister said it was not "a reasonable excuse" to have forgotten about the weapon.