Ebury bridge is an 8 minute walk from Victoria station:

Circled on the mini map is Victoria station.
Edit: I did find the spot where the wall is out of the way, it is on the access road to the British Transport Police.
From here we could go down Warwick way, past Westminster Cathedral, to St James/55 Broadway then perhaps toward Birdcage walk. Will go with the flow.
I'll be travelling via Charing Cross or Cannon Street then the District line to Victoria. Should be there by 3PM.
My mobile number is 07952 943248, if anyone needs me. I'll be using the underground for a bit but will be contactable.
Batteries charged, mini tripod/gorillapod and camera packed.