Luton Airport is probably the most diverse airport in the country:
-A hub for low cost carriers, with easyJet supplying c5m passengers per annum. Primarily A320, B737 size aircraft operated.
-El Al operate a 'full service' route to Tel Aviv, often on the B767 and occasionally the B777.
-A maintenance base for 3 major UK airlines, as well as supporting third party operators.
-Head offices for the same 3 major airlines.
-FBO facilities plus maintenance. The leading private airfield in the UK.
-Cargo operations.
Just proves how much potential the airport would have if the location was slightly better.