George Willard is probably about 19 years old based on character analysis of the protagonist.
George is a young man, though not a child, and he works as a reporter and starts at age 18. Over the course of the text, George develops relationships with many of the other characters because he is featured in many of the other characters' stories. He has many of the characteristics of a man in early youth...he seeks a love relationship and matures in his thinking as the stories progress.