Penalties for delays:
The CAA, under the auspices of the Economic Regulation Group, sets limits on NATS with regard to how much it can charge for its services, how much delay per flight it can impose to allow it to fit everyone in SAFELY, and other limits. At present, NATS has to perform to a reducing cost to tthe user year on year, at inflation less a certain percentage (I can't remember the exact numbers). It has to do this in the face of air traffic growing at between 4% and 6% per year and a requirement to provide equal access for all in UK airspace. How many other companies have to this type of arrangement?
Because everybody wants to take off at 0900 and come home again at 1700, some delays are inevitable for this to happen safely. Therefore, the ERG agrees an acceptable level of delay (in average seconds per flight) for NATS to do this. If they exceed this figure (and I'm not going to say here what it is but I'm sure if you're determined enough you could find out from public information), then a financial penalty system comes into force.
You might think that this and safety are mutually exclusive, but you should know that the actual delay performance in last year's (safe) operation was not much more than half the penalty threshold level.
Hope this helps.