I don't know why you're apologising, Sue: it is totally unacceptable. Protests don't gain anything from attacks on people and property, royal or not. (I hope there weren't any other attacks of this nature, but not reported because the occupants weren't considered newsworthy. One like this is too many.)
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I appreciate people who are civil, whether they mean it or not. I think: Be civil. Do not cherish your opinion over my feelings. There's a vanity to candor that isn't really worth it. Be kind. ~ Richard Greenberg