When were senior Royals last attacked in the streets of London?

The Charles and Camilla incident prompts the thought that, whatever the swings of republican sentiment in the past and present, the Royals have seldom been subject to violent physical public attack. I'm no expert on the Monarchy but offhand I can't think when this last happened. George IV was intensely unpopular; perhaps we have to go as far back as that. Someone will know.