There is concern that the Bruntingthorpe area would be overrun with twitchers if the date of the first flight leaked into the public domain. That could prejudice the safety of the area - the police don't have enough man power to remove idiots and their little aluminium step ladders from dangerous locations.....
I’d wonder just how Bruntingthorpe plans to ‘keep secret’ the first flight of 558? The aircraft will be pushed in and out of the hangar for a week at least, for engine runs etc, before it finally launches. It wouldn’t take a 60’s ex Kremlin employee, probably still in the black Zlin that used to park on the A15, to predict within an hour or two, just when the nose will point skywards.
Trying to keep the event secret is just inviting problems. Probably almost the same number of people, but complete anarchy rather than crowd control.
This needs a re-think Hoskins!