It's a bugger, that - I remember something similar when I worked in Cornwall. Crossing the Fowey by ferry in a rainstorm, wearing oilskins nand sou'wester (you should have seen me - I was adorable), the rain ran off them and into my wellies!
By the way, I looked up the maker of the Pakamac - one word : "Dissolved" - no date.
We've got stained glass windows in our house. It's those damned pigeons.