Historic system map installed at 55 Broadway

This enamel system map of c.1932 has appeared in the main stairwell of 55 Broadway. I'm sure it wasn't there before unless others here know better.

www.flickr.com/photos/24772733@N05/3435397894/

Seems like a companion of the one at Temple. A pity it's not in reception given that most visitors take the lift!