To make my contribution a bit more useful, just discovered that the location of the proposed hotel is between the US Embassy, Nine Elms Lane and Ponton Road, on the far left of your map. This makes Battersea Power Tube Station a little closer and then it would be only a ten minute walk.

See the accompanying map, where you are supposed to walk from point 35 to 8 (where it still says Embassy of Dutchland).
https://nineelmslondon.com/wp-conten...ction_Site.pdf