The BBC says the big naked dude on a hill is overgrown and invisible, due to a lack of sheep. The caption underneath the accompanying photo says:
The giant was disguised in WWII to stop it being used as a landmark
Sadly there are no photos of said disguise, but I suspect this is close enough:
Orders: Bomb places near the enormous pagan dude with an erection.
Bombers: That dude is too villainy to be a pagan.