Shooting Queen Victoria?

Yeah, they tried a few times, as editor Paul Lay of Britain's History Today notes here.  The historical incident most similar to what recently happened to Charles and Camilla, however, may be the mob attack on the vice-regal Canadian governor general Lord Elgin in Montreal in 1849, when he signed the Rebellion Losses Act into law. The whole scene makes a compelling opening to John Ralston Saul's two-headed biography LaFontaine and Baldwin.

'Course that mob was actually aiming for Elgin.  Charles and Camilla were merely drive-bys