I see that LU is to have another, much longer trial of the 'stand on both
sides of the escalator' rule at Holborn:

http://railnews.mobi/news/2016/03/10...-stand-on.html

The previous trial confirmed the theory that, at busy times, escalator
throughout was much higher if people stood on both sides. This time,
they're testing how to get the message across.