The Tradescant blog tells us that: The demolition (including the removal of asbestos) is under way of Riverwalk House, the former home of the Government Office for London on Millbank downstream from Vauxhall Bridge, near the Tate Britain.
It will be replaced by two buildings of 17 and seven storeys linked by a central podium for use as 121 residential units with possible river-facing cafe/restaurant/gallery at ground level. The architects are Stanton Williams.
The dog-leg stairs from the river walk to the bridge will be replaced by a more straightforward arrangement and possibly a lift . The riverside walk will be “maintained and enhanced”.
The existing building was completed in 1965 by architects Falmer & Dark. Its 0.3 hectare site includes a bronze sculpture by Henry Moore called Locking Piece. I haven’t been able to discern its fate.