This domed style with medium width brim is the hallmark hat of the Great War.
As with all hats the hairstyle underneath had a large influence on the design. A transition had taken place from the wide hat supporting hairstyles of Edwardian years through side-swirl styles to these modest centre or off-centre parting styles of the Great War.
In most hairstyles from this time the longer hair at the back will be coiled in a bun or controlled by some other method. There would be enough bulk at the back to use a hat-pin if required.
It is plain from photographic evidence that this hat and the falling collar were contemporaries .
So popular was this style of hat, it was chosen for many women's uniforms.
Usually this hat will be decorated with hatband of wide ribbon
Written on the back Muriel K. Beverton x Oct 1916