New ideas have emerged to aid in London's downtown vision. They include an expanded Grand Theatre and a expanded Museum London.
The Grand Theatre may be able to integrate the proposed performing arts centre into it, and Museum London could absorb other facilities like the Children's museum and bring it downtown.
Gallery here: http://www.lfpress.com/news/london/2.../19849136.html
Cost: about $200 million, bringing the grand total for the vision to about $700 million in 2012 dollars.