UPDATE: Several people pointed out that the map was oriented wrongly. I think I’ve corrected it now, but please feel free to correct it yourself (.kmz file), and send me a more accurate version! Incorrect version was here.
Here’s the map of the Blackheath Cavern from 1946 (mentioned in the previous post) overlaid onto Google Earth. I couldn’t work out how to get it into Google Maps unfortunately. Zoomed out version below (old map is in the top left corner, village is at the bottom).
Blackheath Map of Caverns from 1946 overlaid on google earth
Licensed under a 
I think you have overlaid the plan on the wrong curve in the road – the north point is pointing east. (Also true position was shown to a few of us on Anthony Durham’s underground Greenwich walk last year.)
Meanwhile, interesting subterranean happenings on other parts of the Heath . Last week’s mains burst in Goffer’s Road left a gaping subsidence pit off Duke Humphrey Road. No prob, I thought, just a bit of infill. But the diggers look as though they are aiming for Australia after dropping in some huge circular liners. Who knows when other holes could appear?