Why do the post office change the colour of the stamps even when the value stays the same.?
First the post office do not change the colour of the stamps, Royal Mail do, the post office just sells them on behalf of Royal Mail. The colours change when the function of the stamp changes. Recently the 50p stamp changed from being worldwide under 10 gm surface to being europe under 20gm air so the colour changed. There is also an element of cashing in on stamp collectors as Royal Mail make more money from collectors than they do from delivering mail.
