Wrt ambassadors, wasn't there a Bulgarian(?) assassinated in London,via a poisoned umbrella ferrule?
And the Israeli ambassador was shot in 1980(ish-he didn't die from his injuries for 20 odd years after though he was hospitalised all that time)- but there's plenty of precedent without drawing allusions to 1914.
John Simpson is on Panorama tonight, and the BBC blurb makes the point that even now, the 70-90s were more dangerous in terms of terror - those of us old enough will remember Baader -Meinhoff, the Red Army Brigades, the alphabet soup of all the differing Palestinian factions. Sometimes, it doesn't feel like it, though
And anyone, no matter their cause, is scum to try to maim and kill, especially civilians, to further their ends. Profoundly as I dislike Ms Hopkins and her views, I don't actually believe that makes her equally evil as a perpetrator, financer or supporter of terror.