In Lancashire, we still have a daily delivery of milk in bottles with a silver-foil cap. In the spring and summer, the milkman puts a flat stone (left nearby) on top so that the bluetits can;t peck through the foil. He drives quite a distance, so uses a diesel truck for deliveries, but plenty of places still have the electric "milk float."

I also remember the cardboard caps with a tab, wow - at school in the '40s and '50s the free milk for the children came in 1/3 pint bottles with that sort of cap. It also had a perforated round area in the middle of the cap that you could poke a straw through to drink the milk.

As to Faldages original enquiry - if y'all remember what that was - could the 'heightened awareness' (which is what I believe you were searching for) be termed "altasensitivity" ?