British Airways and Aer Lingus parent International Airlines Group saw premium traffic in February increase by 7% year-on-year.
Overall group traffic was up by 15.8% as capacity rose by 14%.
BA announced plans in the month to start flying from Stansted this summer adding a fourth London airport to its network.
The airline will start flights to Faro, Malaga, Palma and Ibiza form May 28.
The services will be operated by wholly owned subsidiary BA CityFlyer using 98-seat Embraer 190 jets, which are usually based at London City airport.