Mighty Gem, that rather goes to prove MBJs point - the prison phone up the control room of the people least likely to spring someone from the pokey. Who would they ring if a helo they didn't recognise came flashing in over the fence - by the time they had thought about it, they would probably be too late.
The home office mentality in this case is like making military pilots sign for and avoid Royal Flights - we are the least likely people to cause problems and are kept miles away whereas anyone in a Cessna or R22 can airprox them with impunity.