Hmmm...?

I'm not sure about this one. I've passed it plenty of times, and I still can't figure out what, exactly, it's meant to represent. As far as I can see, it looks like a bloke in a suit of armour, carrying a ladder, and holding some sort of tool in his hand. I'm stumped. To the best of my knowledge, I've never seen anyone dressed in the same manner, either entering or leaving the building, much less anywhere else in the city.