Secret Squirrel
There are many permutations and combinations that determine the departure order and it can be difficult to provide the full picture to all the aircraft involved. Our delays are based on push & start request times to airborne. We try to be as fair as possible, at the same time utilising the runway. Some pilots call up to ask 'where they are in the queue' because they feel others are departing unfairly ahead of them, this particularly the case with airlines who only have a short taxi to the hold, which can be frustrating for us when we're busy! (This comment not directed at yourself as you travel mostly from the North Terminal - just a general one!)
All the factors taken into account are inbound/outbound demand, start request times, Aircraft type/performance, SID, Slot etc... Basically we won't necessarily depart you in the order you arrive at the hold. On the other hand we do sometimes get you away earlier than you may expect because your A/C type/SID may be ideal for the situation at the time. All in all you should NEVER be penalised for safety issues. If it happens again make a note of the times involved and call the ATC Watch Manager on your return to Gatwick. We can very easily listen to the RT recordings to try to give you an explanation. Most of us take pride in providing you with the best possible service!!
Happy landings! (& Take Off's!)