Last time I looked at the figures, Luton was handling over 10m pax per year and then add in all the Biz Jets!
In order of passengers per year:
1 Heathrow
2 Gatwick
3 Stansted
4 Manchester
5 Luton
But then again, Luton is a quiet regional airport!
http://www.caa.co.uk/docs/80/airport...K_Airports.pdf