As someone that was working airside at LGW when it closed, I can categorically state that the snow was very heavy all night. the de-icers couldn't clear the snow on the aircraft as quickly as it was falling!
The 50 mile drive home at 4am was treacherous as well. We had over a foot of snow just last night. The trains aren't running, the buses aren't running. I don't think the airport authorities had any option other than to close.
Shinobi