The flag swinging was the exploit of a silly young ass high on adrenalin and who knows what else. No damage was done. The attack on the Glastonbury thorn may have been an act of revenge on the owner of the land- who is currently implicated in a case of serious fraud. The thorn has been chopped down before- and replanted. The current tree on the site- far from being of great antiquity as its mourners tend to assume- was planted in 1952- which makes it younger than I am.
I despise cultural vandalism, but the best way to be defended against it is not to turn things into idols. The Cenotaph is a big block of stone, the Glastonbury thorn is just a tree. They are not the things they represent. An idea- if it's a good idea- survives the desecration of its symbols.