From about 1901 (right after the Victorian period) up to about 1910, or even as late as 1918 (after World War I), British society suffered a very rigid system, despite the new philosophies and politics floating about. The want (and need) for more liberal thought and a move for greater social acceptance of all British started despite the seemingly unmovable morés at the time.
The Edwardian Period was also known as the Belle Époque (Beautiful Era), a time for elegant masquerade balls with gorgeous gowns and absurd masks such as this, our out older doctor with a reflective monocle.
This mask arrives flat and is simple to wear with black ribbon on either side for securing your mask. It measures about 10-1/2 inches.
You certainly won't want to get anywhere near this sick fellow, that's for sure!