Not seem this but sounds very funny.
I recently have recently had further email communication with the station management
regarding why they don't let passengers use the escape staircase as well as the escalators and received a weak answer arguing private vs public areas of the station. I have tried to move it up a level but have received no reply to date. I recall when the overground first opened you could use that staircase and avoid the crush but they seem to have conveniently forgotten this.