A sport is the common term. Many similar camellias (Eleanor McCown is the name of the one I had) have this behaviour. My EM had a branch where the flowers were all slightly different. Most were all pink (no splatches), others were like yours and so forth. My pooches destroyed the plant chasing squirrells so I did not get to enjoy the plant more than 2 years.

It might also be a graft chimera.

Here is a link that might be useful: Wikipedia - graft chimera

So I guess it could turn out to be almost anything? This will be an interesting story!

I can tell you a story to muddy the waters even further.

At a house we used to live in, the front yard by the street was lined with... blast it, I can't remember the name of them to save me now. Woody tree/shrubs, big purple flowers on them, commonly used in the South as a decorative/landscaping plant. Oh well, exact name isn't important. Whats important was that the front of the yard was lined with these things, and they were deep purple.

Then one day a speeder crashed his car into our yard, mowed right over one of those trees. It was bent over, broken, we expected it to die. It didn't, but to this day it blooms *WHITE*.

We joke that the car knocked all the purple clean off that thing.

So yeah, mechanical/environmental damage most certainly can change the color of the flowers.

Maybe an althea/rose of sharon? Interesting comment. I have one similiar. When I was young we had a black dog that got really sick and they gave her all kinds of injections in her side. All the hair fell out at the injection site and when it grew back it was white and always stayed white. Trauma is not good it seems.

Could be Carter's Sunburst. It sports white pink and blush striped on same bush many times. I have one w all 3 colors every year.