Boy,12, beats air crackdown.
The youngster, who had run away from a care home in Birkenhead, Merseyside, walked on to a plane at Gatwick Airport bound for Lisbon at 6am on Tuesday.
Despite airport security being on red-alert following the alleged terrorist plot to bomb planes, he managed to get through airport security, get on the plane and was settling down with a drink and a snack when a member of the Monarch Airlines crew realised something was amiss.
A security alert was raised and the boy was escorted from the plane by two police officers.
The boy, believed to be from Penrith, Cumbria, has now been returned to his care home.
He is understood to have got to Gatwick by train - unaccompanied and without a ticket, which he has apparently done on a number of occasions.
His mother, who cannot be named, said: "My worry is that if you have terrorists in these airports they could be looking round for someone who is vulnerable, and get them to take things on the planes for them.
"What happened is frightening, especially given the state of alert we are supposed to be on at the moment."
BAA Security launched an investigation.
* British Airways passengers endured more flight cancellations today as the airline struggled to reunite people with their luggage. BA said it would not be until Friday that its full service could be resumed.
BA cancelled 46 flights today - 35 at Heathrow and 11 at Gatwick, taking the airline's total cancellations since the anti-terror measures were introduced last week to more than 1,100.
BA said it would be cancelling 19 short-haul flights out of Heathrow tomorrow.
The airline said it understood that as many as 20,000 bags had gone astray at Heathrow in the past few days - the bulk of them BA passengers' luggage. Today the airline was still trying to get about 5,000 bags to owners.
Ryanair, which was hoping to run a cancellation-free programme today, has criticised the new hand luggage regulations as "nonsensical" and the Federation of Tour Operators said travel companies had felt "let down by inconsistent airport policies and clearly inadequate staffing arrangements".