I don't know much about postcards, so I will describe what is on it and scan front & back to show its' condition.
I presume it is a postcard that would of been purchased from the 'Museums' gift shop.
Front: A black & white photograph of some workers with scythes.
Back: Woolstaplers Hall Museum, Chipping Campden, Gloucs.
I have no idea if it is rare or not and I have no idea of its' monetary value -
hence low start with no reserve
Please see pictures.