Could anyone identify what service this woman belonged to (WWII, UK)

[snuttall]

One of these women is my grandmother, who was born in Feb 1928 and was only 17.5 years old when the war ended. So I would also be interested to know if this was likely during the war or perhaps afterwards? Thank you

Link to image: https://ibb.co/rFXF06M

[ShaunJ]

WRNS

https://en.wikipedia.org/wiki/Women%27s_Royal_Naval_Service