10W et al,
The bit in the Atkins report you've missed is the statement that the extra flights such as head of state, Olympic family and busness flights will generally take place during the 3 days before and the 3 days after the main Olympics.
This makes the figures even worse as it is not spread over the whole of the time the Olympics take place.
Then on top of that there is, as you state, the anticipated extra helicopter flights (upwards of 1300 per day, allegedly) and the fact that Paris is putting a lot of effort into selling itself as the place to stay for the Olympics... nicer, safer city than London (not my words), and only a short hop across the channel... and that hop will be done by aircraft in the main if Paris gets the numbers of visitors it wants... Eurostar does not have the capacity.
Allied to all this is the fact that there is new temporary restricted airspace with a few rules attached... the LTMA already suffers an inordinate amount of infringers (though it has improved drastically over the past 2 years). These infrngers tend to be from local airfields that you would expect to know better... throw into the mix people flying around who don't have a clue about the airpace and it could be fun.
The main traffic will be fine. It will be busy but as usual the engineers, ATSAs and ATCOs will make it work (despite the best efforts of management
).
The problem will come from responses to infringing aircraft... UK PLC will (rightly) be a lot twitchier than normal wrt security. I'd anticipate that response will be less measured i.e. less time taken for intelligence gathering before sending in assets to investigate, with the usual ensuing knock on effect in very busy airspace.
That is, in my opinion, where the biggest problem could arise.