Jim, possibly the open site opposite "the Dome" at N51 30' 08" E00 01' 07.28"?
That one looks good from a pilot's point of view, certainly if the photos of that area on Google Earth are still accurate. No housing adjacent; it looks industrial all round. 350m x 200m estimated, with a road running immediately to the north of the site.
The City desperately needs a new heliport so let's hope this comes to fruition very soon, preferably one near an Instrument approach path which would help for bad wx operations.
Also, someone could make a small fortune running a boat ferry across the river to and from the Olympic Games site.
