4th West York Militia officer’s 25mm button

A 25mm, officer’s post 1881 tunic button of the 4th West York Militia with design of the title FOURTH WEST YORK beneath the rose and crown, It has the backmark JENNENS & Co. LONDON. A variant of the regimental butons which usually use 4th rather than FOURTH. I am a little puzzled by the metal of this button Howard Ripley describes it in his book as being silver but this example seems to have a bronzed finish, perhaps just a form of toning as it has been  in my old collection and is uncleaned as usual.  nov13/1