I live very close to Greenham (though didn't when it was active) and occasionally go cycling with the kids up there.
On my last trip we cycled the length of the runway - the mid-point intersection for some reason wasn't dug up and is still there. At the Eastern end, I found a set of 4 cables sticking out of the ground each side of where the threshold would have been - almost certainly the wiring for the PAPI's.
The "bunker" area is still very much sealed off - an eerie piece of modern history.