How to hang mail art on the wall like a duchess

The Duchess of Devonshire at Chatsworth (very near Tideswell, the town in England where my father grew up), celebrating her birthday by taping all the mailart to her walls.  Whatcha think?  Masking tape or that sticky stuff that promises to come off without ripping off paint?  In truth, I suppose the butler did it.

Vanity Fair, November 2010, page 156