An unaccompanied 11-year-old boy boarded an international flight from Manchester without a passport, ticket or boarding pass, prompting a high-level security inquiry in the last days before the Olympics.
Liam Corcoran escaped from his mother while she was shopping in Wythenshawe, south Manchester, and got to the airport three miles away.
Once at the airport, Corcoran, who was said to be fascinated by planes, passed through five security checks before boarding the Jet2.com flight to Rome, trailing a family of holidaymakers to avoid detection.
Reports suggest the cabin crew did not even check Corcoran's boarding card when he stepped on to the plane, or carry out a proper headcount of those on board before the flight took off in the early afternoon.
Corcoran was brought to the attention of the cabin crew by passengers in mid-air, and flown home on the return flight. It is thought that the flight from Rome to Manchester was delayed by around 80 minutes while the flight crew were interrogated by Italian border police.
Airport security staff, ground and cabin crews were immediately suspended and a probe into the incident has opened.
"This extremely serious matter is now being urgently investigated. It is clear that documentation has not been checked correctly at security and the boarding gate. The boy went through full security screening so the safety of passengers and the aircraft was never compromised," said a Manchester airport spokesperson.
One of Liam's fellow passengers, 26-year-old Sarah Swayne, told the Manchester Evening News: "He was very talkative and seemed quite un-fazed by it all. He was just sat there chatting away about how he'd been trying to run away from home.
"He seemed quite innocent really and I don't think it had sunk in how serious the situation was."
The security breach is likely to provide major concern for Manchester Airport bosses, with immigration staff about to strike over border staffing cuts.
Border Force staff at Terminal Three will stage a 24-hour walk-out on 26 July, a move which has already forced the closure of the Terminal to international arrivals.
The strike is part of a wider campaign of action by border officials across the UK, orchestrated by the Public and Commercial Services Union.
With the Olympics about to begin, the Home Office has branded the strike "irresponsible", adding:
"We ask members not to walk out at a time when the eyes of the world are on the UK, and thousands of overseas visitors are arriving at the border."