UK - large town with half a dozen congregations.
I attended book study from 60's until it ended.
Brothers always wore a tie and never jeans.
Hot summer (UK - 25 degrees C and above) dress shirt, tie, meeting trousers.
Cold winter (UK zero and below) suit or sports jacket, sometimes a sweater. Always a tie.
Sisters always had skirts or dresses.
Exceptions - snow on ground, unable to drive and so might walk in jeans, walking boots. Sisters too.