I think you'll find that four additional 'finger' stands capable of accommodating x 1 each B737-800/A319-size aircraft, will be constructed at Luton east of Taxiway Delta, opposite the current East Apron.
The fitting out and opening upper storey of the 'new' terminal building is dependant on additional services/operators taking the annual passenger throughput above (I think...) 8M (planning consent) as is the construction of a boarding pier and air jetties to serve the North Apron stands and the north side of the East Apron.
The additional services/aircraft were Now and Ryanair, neither of which has materialised. Therefore, TBI's plans remain on hold until the expenditure can be justified.
Unlike a certain Big Airports Authority, TBI doesn't cross-subsidise its Luton operation (loss-making East Anglian airports from other more lucrative locations...) and unlike that Big Airport Authority, it has to pay the hard up Luton Borough Council, £3 for every passenger it attarcts into using Luton, before any cash comes into the airport operator's coffers.
This compares with around £2.70 for each passenger using the cross-subsidised Big Airport Authority's East Anglian Regional Aerodrome...
Manston?
Well, it DOES have a fantastically long runway...
