An equally reliable 'mole' says that LLAO's parent company (ACDL) is stalling on additional expenditure for the existing site as it believes this would be unnecessary and wasted if the new runway and airport is approved.
So the full signs would go up next year then with Luton turning away business for the following 5 years. The problem is more likely to be the limited additional income generated on the capital invested for such a short period while the new terminal is being built. Once a new terminal is constructed then I would assume that at least half of the passengers using the present terminal would move to the new terminal so the additional build would no longer be needed.