Looking at
https://en.wikipedia.org/wiki/London...d_destinations
Ryanair - 10 routes - Alicante, Bergamo, Brest, Bucharest, Corfu, Dublin, Faro, Malaga, Palma, Reus
Wideroe - 2 routes - Bergen, Kristiansand
Wizz - 1 route - Bucharest
Total - 12 routes