The most popular garment worn by young women in Britain during the Great War and seen in countless photographs was
the V-necked blouse.
Edwardian blouses were elaborate high necked garments.
At the time the V-neck was a major fashion departure.
Most of these blouses were button-through style with little shaping. You may see the bodice gathered into the shoulder and a few shaped collars; otherwise they are always simple in design, nearly always in plain white fabric.
You will will hardly ever see a blouse worn without a Modesty Brooch marking the lower limit of the V.
....I had...a white Lillie Elsie V necked blouse worn open as low as I dared.
from "Look Back with Mixed Feelings" autobiography of Dodie Smith (who wrote "101 Dalmations")
The concept of the Modesty Brooch is not as simple as it seems.Some brooches are worn extremely high. Some seem to serve no purpose apart from as an ornament.
Whether they should be seen as a " fascinator" with the intent of attracting attention or as a safety device is unclear.
Where they were positioned was certainly in each woman's individual control.
The majority were modest pin brooches but naturally in a country at war many took the form sweetheart brooches.
These can establish a connection with a particular service or regiment.
In full length portraits you will usually see this blouse worn with a corselet skirt.
By about 1918 it became the fashion to wear a small ribbon bow in place of a brooch.