I have historically been a "soft" monarchist. I think the monarchy has considerable soft power benefits and makes a great tourist attraction. I started going off it a bit though seeing just how much the cost was in relation to other European monarchies.
And then this whole "swearing allegiance" thing has rather crystallised it for me. Will I swear personal allegiance to Charles Windsor? No, of course I won't, he has no more right to my allegiance than does my next door neighbour. And therefore how can I consider it right that he is "my" king?
I can't, of course. It follows that I must believe that disestablishment of the monarchy is what should happen. So there's my changed opinion for today.
@epistatacadam I have a certain amount of respect for him as a person. As you say, environmental concerns, plus he's had to spend his whole life in his mother's shadow and now in her shoes. Not easy. But I have respect for lots of people without developing an urge to swear allegiance to them.