preston sighting ? 1990's

in 1992 i took a security guard job for a short while at cranswick foods preston, my job was basically sitting in a gate house on a night shift and doing what most security guards do, watching TV. the gate house had large windows on all sides with a reasonably good field of vision. one morning about 2am i had just finished my patrol and got sat down with a cup of tea, turned on the TV and turned the lights out in the gate house as they made it hard to see outside due to reflections on the windows. as i was about to turn the TV over i saw a silhouette of a man looking through the front window, as i looked up the silhouette had gone. i focused back on the TV and the silhouette was there again and this time i saw it move away, my first thoughts was that the other security guard was messing about, as i stood up and started to walk to the window i saw the silhouette out the corner of my eye, this time standing in front of the right window, i turned my head to the side and saw the full figure looking back at me. it moved away to the right at unnatural speed like vampires do in hollywood films and stood at the rear window, i spun around and we looked at each other for no more than a second before it darted off again, this time gone for good. i have never seen anything move as fast in my clueless as to what it was but i know for a fact it was not human but human shaped if that makes sense. i could not see any detail only a blacked out silhouette. i have looked on the internet for similar stories but only come up with shadow entities etc, it was definitely not one of them.