i mean £1 a window the rectangular thing, the bottom ones maybe £0.75, it is a first clean, and they are dirty, i could see them needing two cleans to get them right,
and it looks like a play ground and low windows, that means small children with disgusting, sandy, greasy, poohey, hands all over them windows,
i used to clean windows like that in a school, daily, everyday they where caked,
i cant see, but i bet the tops are black, the bottoms are not so visible dirty i.e black dirt, but just hand prints etc etc over them,
think about spraying some TFR on them first, or first clean with soo gg3 just too loosen that dirt