The passenger handed the weapon straight to flight attendants after mass panic ensued. Such a terrifying discovery forced the plane to be grounded for more than an hour due to the commotion. Passengers were calmed down by a pilot announcing that close-protection officers were allowed to carry guns on board, but one passenger refused to accept the situation. The standoff eventually ended with the gun being removed from the plane.
The retrieved weapon is thought to be a 9mm Glock 17 pistol that the close-protection officer had taken off his weapons holster and forgotten to pick up again.
A source said they were thankful it had been picked up by someone who did the right thing.
“If it had been found by someone with malign intent it could have turned into a very serious incident for everyone on board.”
Scotland yard confirmed that an officer on David Cameron’s protection team had been suspended from operational duties pending an investigation.
In a statement, the Metropolitan Police Service said: "We are aware of the incident on a flight into the UK on February 3 and the officer involved has since been removed from operational duties. We are taking this matter extremely seriously and an internal investigation is taking place."
Mr Cameron is automatically entitled to round the clock armed protection for life, and taxpayer money funds them to travel with the ex-PM around the world.
Previously his guards have faced criticism for allowing a jogger to collide with him on a visit to Leeds.
This latest humiliation for the police could raise questions about whether bodyguards should be entitled to keep their weapons on board aircrafts.
Mr Cameron’s office had declined to comment on the latest incident, only saying it was a matter for the police to investigate.
It comes after Mr Cameron handed his resignation in after he had campaigned remain in the 2016 referendum.
Since leaving office, he has tried to keep a low profile but has been raking in cash by providing speeches for large corporations around the globe.
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In accounts that have been released last week, it showed he has generated £800,000 in revenue last year from public and media appearances.
Mr Cameron published his memoirs entitled “for the Record” last September and has recently taken a job worked as the chairman on the advisory board of US artificial intelligence company Affiniti.
He is among serval other high profile figures listed with the Washington Speakers Bureau, a US-based agency. Others include Alastair Campbell.
One one occasion Mr Cameron was paid £120,000 for a speech to a financial company in New York.
Although Mr Cameron is now making more funds than when he was prime minister, he is not in the same league as former chancellor George Osborne who currently holds nine jobs.
Mr Osborne is the editor at London’s Evening Standard and holds a £650,000 advisory role at BlackRock, the asset management giant.