(Thank you to Alx for this link!)
The King and I by Jonathan Gregson
Jonathan Gregson is the author of the books Kingdoms Beyond the Clouds, about Himalayan kings, and Massacre at the Palace (also called Blood Against the Snows), about the royal family of Nepal. I've read Massacre at the Palace and found it interesting and informative.
(The headline is misleading; the cake was baked for Queen Elizabeth way back in 1992.)