The notice about the closure was hardly high-visibility was it? I didn't see it until the night before the closure (and promptly forgot about it the next morning prompting a frantic dash around the other side and over the bridge!)
It will be immensely frustrating if there is no sign of any "maintenance work" having been done. Platform 2 is terribly inaccessible for anyone who has trouble with steps, so one would expect that gate to always be open except in emergencies.