I only need to look at this thread to see that's it's a good deal more complicated than that.
With the royal portrait hoo-hah, a memory stirred about an anecdote related by one of my teachers. My school was, and still is, a Catholic grammar school. This particular teacher was one of several Irish Christian Brothers, and had taught there since the school was founded, some 30 years before I arrived.
The story that he told was that, when the school became a direct grant school, there was a Government rule that no religious images were to be displayed in the classrooms. So, whenever the school was to be inspected, the statues which adorned each room had to be hidden away, to be retrieved after the inspectors left. The rule was no longer in force by the time I was there.
Now, a statue is basically just plaster and paint, but in this context, the statues were heavily symbolic. To the teachers, especially those who were in Holy Orders, the statues represented an aspect of their religious faith. To the inspectors, they represented religious indoctrination. To any random visiting Protestant, they might also have represented idolatory and superstition.
In the same way, a picture of the Queen is just a picture of the Queen. But that picture has symbolic power of different types, to different people.