Whitechapel Station temporary ticket hall on Durward Street

I was at Whitechapel Station last Friday. The temporary ticket hall on Durward Street, which will be accessed via Court Street, is turning into a much more substantial building that I expected. A plan view is shown on page 6 of this planning document. This photo shows the building and the stairs that will lead up to it:

IMAG2035 by dmncf, on Flickr

But according to this poster on the platform it should have opened in 2014. If I worked on the site, I would have got some Tipp-Ex and amended the poster myself by now! Does anyone know why the work is behind schedule?

IMAG2036 by dmncf, on Flickr