For those with long memories when the new terminal opened in 1999 the check-in area was so dark due to a lack of lighting that anyone with cataracts was ill-advised to use Luton unless they brought a torch with them. Maybe 10 years later the airport put in supplementary lighting.
I would like to think that Luton will finish off the ceiling to the original specification within the next 10 years as even when the retail units fully open the roof space looks like work in progress.