Prime Minister David Cameron left his official red box alone on a train - to nip to the buffet car.
Mr Cameron, who once left his daughter Nancy down the pub, strolled off down the aisle without the crucial briefcase.
The battered red box, emblazoned with the words ‘Prime Minister’ on the side, was left for all to see - with the key still in the lock.
Mr Cameron was travelling to a family wedding up North on the packed East Coast main-line train, leaving passengers in the carriage stunned.
These exclusive pictures show Mr Cameron’s red box perched, unattended on his train table - surrounded by four empty chairs where he had been sitting.
One gobsmacked passenger stopped to take a picture - without any security guards intervening.
He told the Mirror: “It was just sitting there. I could probably have run off with it if I’d wanted to.
“But instead I took a photo of it.”
Cameron works on a train Former government minister Kevan Jones last night told the Mirror he was amazed by Mr Cameron’s bravado.
He said: “I was never allowed to take my red box on public transport. There were very clear rules.
“It’s astonishing, quite frankly, that he would just get up and walk off down the aisle.
“There could be any number of state secrets in that box.
“What would have happened if someone - for whatever reason - opened the window and chucked it out?”
Mr Cameron’s carelessness will spark outrage - as it comes after Transport minister Simon Burns claimed he couldn’t use public trains - because he was barred by official rules from working on confidential papers on the train.
The revelation is reminiscent of the time Labour Cabinet Minister James
Purnell sparked a security row after losing confidential documents on a packed train.
Mr Purnell took documents out of his red box on the trip - breaking strict protocol.
Edinburgh-bound: The East Coast train Ministers are warned against taking their Cabinet briefcases on public transport amid fears secret papers could be lost or stolen.
Former Cabinet minister Peter Kilfoyle set out guidelines on carrying red boxes in 1999.
He said: “Where it is necessary to carry red boxes by public transport, they should be effectively disguised.”
Former Deputy Prime Minister John Prescott told the Mirror: “I’m staggered that a Prime minister should be so slack about looking after Government secrets.
“The box could have contained detailed confidential intelligence about Syria. I never let mine out of my sight.
“It’s also a bit rich that his Government persecuted journalists for carrying secrets but left his own on his table while he went to the buffet car.
“Talk about Inter Twitty. The guy needs to get a grip.”
Mr Cameron was on the 7.44am train from King’s Cross to Edinburgh on Saturday leaving from Platform 1.
One witness, who had boarded the train late and was walking through the carriages looking for a seat - spotted Mr Cameron in the buffet car, which was closed at the time and empty apart from a ticket collector.
The man, from Essex, thought: “That’s a face I recognise.”
He told the Mirror “I carried on walking through the train and two carriages on I saw the PM’s red briefcase on a table all alone.”
The red brief case, clearly marked ‘Prime Minister’, was left unattended on a table with four seats.
A man was sitting on a pair of seats on the other side of the aisle, but he didn’t appear to mind a stranger taking a picture of the briefcase.
There was a man sitting in a seat of four behind him and a woman sitting in a seat of four behind Cameron’s chairs.
Our man said: “First of all I couldn’t believe that Cameron was on the train unprotected - I just walked past him.
“I could freely bump into this guy and there was no security or anyone around him
“And secondly it was incredible that his briefcase was lying there just like that.
“I could have quite easily have damaged it or scratched it or run off with it.
“And above all I couldn’t believe the key was in the lock.”
The witness said it took 30 seconds to walk from the buffet car to the table where the PM’s briefcase was.
Country do: Cam and Samantha arrive at the wedding PA
Mr Cameron got off at York where he went to the country wedding of Samantha Cameron’s sister Alice Sheffield.
Fresh from the G20 summit in St Petersburg, Mr Cameron was seen taking pictures on his mobile phone outside Sutton-on-the-Forest Parish Church near York following Alice Sheffield’s wedding to Etienne Cadestin.
Ms Sheffield once worked for Mr Cameron as a correspondence secretary and is the founder of green cosmetics website Bare Faced Cheek.
Family wedding: Alice Sheffield - Samantha Cameron's sister - wed Etienne Cadestin PA
Her new husband, Mr Cadestin, is a senior sustainability and energy consultant for estate agents Knight Frank.
Mrs Cameron and her half sister are the daughters of baronet Sir Reginald Sheffield.
The wedding meant that Mr Cameron was unable to attend the Highland Games at Balmoral.
Traditionally the Prime Minister spends a weekend with the Queen and Duke of Edinburgh in September and it often coincides with the Braemar Gathering.
But Mr Cameron will instead visit the Queen’s retreat later this month.
Last night a No10 spokesman said: ‘The box was not left unattended.
“The Prime Minister’s security detail was there at all times.”
Rubbish bin blunder by David Cameron's aide
David Cameron’s top adviser Oliver Letwin was caught by the Mirror dumping secret papers in waste bins in St James’s Park, London, in 2011.
Over five days he threw away 100 sensitive pieces of correspondence covering terrorism and national security.
Three years earlier former Work and Pensions Secretary James Purnell walked off a packed train leaving confidential documents behind. They were picked up by two women and he got them back three days later.
Housing Minister Caroline Flint was photographed with a house prices briefing entitled: “We can’t tell how bad it will get.”
And the Treasury’s Danny Alexander let slip the coalition expected 500,000 jobs to go drastic because of spending cuts.
#dailymirror
