Seems that British Pathe has uploaded masses of clips to Youtube from the archives, a quick search shows there is rainwear to be seen among the vids. I put in a search of Britsh Pathe rain and got al this lot
https://www.youtube.com/results?search_ ... pathe+rain
havent looked at them all, but you get things like this https://www.youtube.com/watch?v=k8h8uzkIJUY
feel sure someone will come up with some gems amongst them all