&searchp=ids.srf&mapp=map.srf]London Map
View the map in 1/25000 at the above site. Here is a section of the map with three elevations shown. They were taken from Google Earth, and are in feet.
![](http://i195.photobucket.com/albums/z117/riegelpete/ElevationsCropped.jpg)
Note the three elevations appearing in red. They were obtained using Google Earth. To the left of each red elevation is a figure which shows the elevation in meters, according to the Landranger 1/25000 map. There’s quite a discrepancy.
Mike Sandford and I have been kicking this around. He converted my readings to meters and said:
OS map * Google * so google sea level datum is lower by
16 meters * 29 meters * 13 meters
2 meters * 15 meters * 13 meters
4 meters * 16 meters * 12 meters
The Thames moves up and down with the tide, and the Embankment, which borders the Thames, is considered to be about 5 m above mean sea level.
These are the biggest differences I’ve seen between Google and a trustworthy map.
Check it out! Any thoughts?