Not necessarily - it's winter there - dark early (15:30 Zulu was lights on), and it's been a foul week for weather around LGW - I was there (or nearby) at the time - low cloud, showers, very poor light levels all day . There are birds, blowing trash bags, leaves in the air. It's very very hard to judge distances
Hard enough to spot a drone in a clear blue sky - and once one person says "is that a drone?" then you've got everyone pre-programmed to "see" one
I suspect that someone MAY have been flying drones around the area - one of the local guys told me there are a couple of oil well sites they've been protesting about a few kms away from LGW and the protesters use drones to spy on the oil works - but they may have been well outside the airfield boundary.