Squeezy flight from GVA to LGW. Crew counted an extra passenger before door closed. Announcement made, second announcement asking everyone to check their boarding cards for flight number destination. Flight number and destination repeated while everyone did same. Finally an announcement please have your boarding cards ready for inspection ... All of the above done in English only (U2 aircraft and crew)
They found the culprit, backpacker who spoke some English, headed for Luton which was boarding from adjacent gate.