Had a quick ride around Wicken Park and Tattersett business park this evening.
No sign of any security.
Yes there are fences separating the parks from the runways and control tower and padlocked gates on the roads leading to them. The buildings on the parks are shuttered.
So I would say that if you entered any of the buildings or crossed over the fence, then you would be committing an offence.
What you could be charged with I don’t know.