Just a tidbit from the tail end of a Sankei article, but it was revealed that Hitachi Rail has been working on a rolling stock design proposal to pitch to London Underground. The project was started three years ago. It is projected that around three thousand carriages will have to be replaced in the 2020~2030 timeframe. The projected design will have airconditioning (a first apparently), as well as walk-through (open gangway) carriages.
http://www.sankei.com/economy/news/150903/ecn1509030032-n1.html