This is a nurse’s uniform hat from the Red Cross from around August 1948. The online guide states: Indoor Uniform: Figure 73 Commando blue seersucker or blue poplin (latest selection since seersucker no longer obtainable) one-piece dress with either long or short sleeves, convertible collar, and 2-inch woven red cross on the upper pocket. Cap: Matching buttoned cap with 1-inch red cross centered on front of facing. 

 

 

https://www.worthpoint.com/worthopedia/vintage-blue-wwii-nurse-nurses-1927456632

https://collectarc.com/Uniform%20Guide.pdf