Author
Drower, George

Title
Heligoland: The True Story of German Bight and the Island the Britain Forgot

Publisher
The History Press, 2002

The focus of the book is on the eras after the Regency, but the book nevertheless excellently tells the story how Heligoland became England smallest colony in 1807.

I found the book helpful for writing my post “Jane Austen, the Captain and the Smugglers of a Tiny Island“.