He can't be a bulldog cross as he could not be parti colored if that was the case. Parti coloring (white background coloring) has to come in from both parents and bulldogs aren't parti (that I've ever heard of). Long coat has to come in from both sides as well (short is dominant). If he was a bulldog cross he'd have to be the solid clear sable color and as well short coated. There is no way around that genetically.
He looks like a beautiful big boy. He probably is a throw back. I have a dog here that is 27 pounds (slim) and his parents are 14 and 18 and none of his grandparents were over 20 pounds. His three sisters are all ~18 pounds. He just decided to be a bit different.
After owning dogs from weighing from 12 to 70 pounds I have to state this big boy is my preferred size.