This is a man's black linen 'Sunday best' smock of a local pattern (dating back before 1880), like those recorded by Gertrude Jekyll in her book 'Old West Surrey'. Jekyll lamented the passing of the custom for men to wear smocks or 'frocks',
" A 'best frock' and a tall hat with long nap, or the usual felt hat, was the Sunday
dress, unless a man had a suit of cloth wedding clothes, which would be his
Sunday suit for life...
... I can remember when one could tell what a man was by his distinctive dress...
... Now, alas! all workpeople... are clothed in a dead-level of shabbiness. The
shops are full of cheap suits with a pretence of fashion, which are bought
for Sunday wear. They are soon past their best, and are then taken into working
use, for which they are entirely unfit."
Old West Surrey, Jekyll, G. (London:Longman's, 1904)
Available for reference in Godalming Museum's Local Studies Library