These parts are numbered 7 and 8 in the illustration from the Vauxhall parts book in the final photo. They are not handed and stop the door glass at the bottom.  ......

I have two of these brackets and the buy-it-now price is for one bracket assembly. If you require a pair please buy two at checkout.    It is well know for these brackets to rust away when water inside the door drips down onto them.    

  Note that a felt pad goes between the bracket and the door skin, -   but this has rotted away and gone to dust long ago,  so a simple fix is needed, a new piece of felt needs to be glued on.