“Border Force officers carried out identity checks and established that he was a British national who previously held a valid passport. The passenger was allowed to proceed after completing paperwork to report his lost passport.
“It is vitally important that airlines ensure they know who is on their planes and carry out proper document checks on passengers. We are investigating the circumstances of this incident with the airline involved.”
Been on a flight many years ago with some late teen / early twenties Sailing types who started off on South Coast of England crewing with some friends, picked up a good wind and ran with it. Landed in Spain without passports or anything, owners stayed with both and kids got to Madrid and parents booked their flights back and Immigration (Pre BA) got called by Airline now no longer in existence.
Immigration asked to speak to each individually and phone handed back to airline staff with a comment "yup seem like some of ours, send them on and ask for Officer X at X Airport". Airline staff member then got a fax indicating that X,Y,Z were believed to be UK nationals and allowed to board said flight to UK. Parents required to be at airport with ID and Passports but that was it, sat next to 2 on way home and they shocked they actually getting home and that people wanted to help them rather than jail them.