Years ago back when I was an engineer we used to keyhold we used to look over wiston house in cissbury http://www.wistonhouse.co.uk/the-house/history/
I have no idea if it is haunted or not but it is a very old building with lots of secret passages and what nots, and I have heard rumours of all sorts going on its quite close to cissbury ring where the devil worshippers hang out.
Anyway I got called out there one wet and stormy night, you know the ones claps of thunder and lighting ect. Anyway I arrive on site one minute to midnight as I am driving up I could see a light on on the top floor, so I am thinking someones on site already. So i get out of the van switch the alarm off and check out the log, alarm was set at 17.00 then nothing till 23.00 when the alarm activates on the top floor landing, and nowhere else, off I go expecting to find someone in the building still working (only the landing on the top floor had detection) get up stairs check all the rooms and I found no one. So I inspect the detector for signs of spiders and the usual environmental checks nothing, cant see any reason for activation. I would normally change the detector at this point but the house was creeping me out a little lots of creaking noises along with thunder and lighting so i decided to isolate the detector (It was trap detection you couldnt break in on the top floor even with a helicopter) switched the lights off, went downstairs, reset the alarm, isolated the zone, set the alarm, got in my van wrote the job sheet went to the house and posted the top copy of the jobsheet through the letterbox walked back to my van and something made me look up, and the top floor light was on again. Now I know I had switched it off and it was not on when I originally returned to the van, I know there was no one in the building I checked every room on the top floor and they could not of come downstairs without triggering another detector or passing me on the stairs there are no secret passages on the top floor. I thought about going back to switch it off for about a second whilst I was running to the van. When we went back to change the detector I spoke to the caretaker and he said that sort of thing is always happening I dont believe in this sort of stuff but at the time this did creep me.