This will be through my opinions of books, I've heard/looked up about.

But the quick thing to comment on, when you say, "positive light." It may be hard to find a book, that comments on just the good things about a certain area. But nevertheless here are some book suggestions about the British empire.

"The rise and fall of the British empire." By Lawrence James.

This book explores the British exploration and expansion from the 16th century all the way to the 20th century. I would recommend reading this if you haven't.

"Ornamentalism." By David Cannadine. This book explores the public opinion on the Empire. And Cannadine also argues the class, rank, and status were more important than to the British empire then race.

"Understanding the British Empire." By Ronald Hyam. This book explores the British empire history. Done by over a lifetime of research, by an expert in this field.

"The Blood Never Dried: A People's History of the British Empire." By John Newsinger. This book is for people that don't mind seeing the negative features of the British empire. The book challenges the idea that the British empire was a kinder and a gentle force. John Newsinger sets out to uncover this neglected side of the history of, repression and resistance.

Sources Google books. Personal opinion.

Well, those are some books. Hope I've answered your question and added some books for you to look at! :)