What is the History of Luton Airport blog?
Gong back to the photo, the "new" terminal shown here was known as the intermediate terminal as it was only meant to be temporary yet it is still in use today buried in the middle of other buildings that have been added over the years.
The grass spectators area is now the location of Easyjet's orange HQ and hangar. The car park became part of the bus station and link building to the 1999 terminal and even that is changing now as building work on the terminal extension is taking place.