i find the best way of cleaning the new style leaded windows, if they are REALLY dirty, is to soap them up first , blade off what you can, them rub with a damp scrim, then microfibre. I no it seems like a lot of work, but that is what you need to do really for DIRTY pub windows.
If they are the old style leaded windows, then you need to just use a wet, soapy scrim and a micro to get best results
Richy