It is the third busiest airport in the United Kingdom and is the third largest airport serving the London area after Heathrow and Gatwick ; and is one of London 's five international airports along with Luton and London City Airports . It is the third-busiest airport in the United Kingdom and the third-largest airport serving the London area after Heathrow and Gatwick ; it is one of London 's five international airports , along with Luton and London City .