Coinidentally,
Flight just published an article on the subject:
How the London Olympics were filmed from above
Extract:
[Aerial Camera Systems] gathered together a fleet of camera platforms and crews. Six Eurocopter AS355F1 Twin Squirrels were sourced, most of them from air operator's certificate holder Excel Charter, based at Stapleford Tawney, Essex. Four of these would be required at any one time; two overlapping to provide a continuous feed during lengthy events, a "hot spare" ready to go and a "cold spare" fitted with a fourth Cineflex V14 high-definition camera system.
Each tail number was issued a Mode S Hex Code, authorising it to enter P111, and Evans drafted and submitted a detailed flying programme to cover the 16-day festival of sport. Downlinks for the high-definition images would be provided by a pair of King Air turboprops stationed at 20,000ft above London. These offered a more elegant and cost-effective system than that deployed during the 2004 Olympics in Athens, where up to half of the 14 aerial filming helicopters had to be dedicated to "re-bro" (re-broadcast).
Away from London, three further ACS Twin Squirrels covered the sailing events off England's south coast - at Weymouth and Portland - from the HM Coastguard helipad near the regatta control. Images from these helicopters were the basis for some ground-breaking graphics by the BBC clarifying the positions of the race leaders. Fly-bys were also required at each stadium in the nationwide football tournaments. By rigging a series of cable cameras, ACS removed the need for additional vertical coverage of the equestrian, rowing and BMX events.
In total, the ACS fleet flew more than 300 hours during the Games, with a further 50 hours contributed by the Weymouth- and Portland-based helicopters.
I/C