An official warning notice has been issued to security firm G4S and all airlines, following the unintentional breach at airport security and then the boarding gate, as the woman was allowed onto the Flybe flight to Exeter without a pass.

The incident has sparked separate internal investigations by both G4S and Flybe.

Airport director Colin Le Ray said it was only a headcount on board the flight that alerted staff there were one too many passengers compared to the number of boarding passes issued for the journey.

Mr Le Ray said the woman had been a legitimate passenger, who had gone through security and the boarding gate as part of a group, but her boarding pass had never been issued to the party at check-in.