Edit to add... we often used to find 'live' ammo up there, take it home, stick it in a vice, and smash the shit out of it with a hammer. Never got one to go off, thankfully. o_O
Thought so.
Now, the white track around Cissbury isn't an anti-tank trench. Why on earth would it be?
It was made by tanks, yes, but only to practice driving skills on different slopes, etc. The soil on Cissbury is only a couple of inches thick in most parts, so a load of tanks would have taken...