A very nice capture - it has really rich, warm tones.
Dolly Horn normally has a flushed pink colour. Those leaves look like they are evergreen in which case the most common evergreen variety would be Magnolia Grandiflora. And as the name suggests you don't get a much bigger flower - they can be as big as 10 or 11 inches across.
I used to have one in my last house but the flowers were always at the top of the tree, they lasted no more than a day or two and could only be appreciated from the bathroom window. I always wanted to get a picture like this but climbing up stepladders with a camera next to the neighbours fence might have got me arrested!