Think celebrities of our modern age are responsible for an obsession with personal privacy? Then you don't know Duke.

I'm not referencing John Wayne here, but rather a 19th-century Brit named William John Cavendish-Bentinck-Scott, aka the 5th Duke of Portland. At least, I think that's who he was. Then again, he could have been successful London businessman Thomas Charles Druce. Either way, both men (or, one man living a double life) guarded their personal privacy with fanatical focus that is detailed in Piu Marie Eatwell's new book, "The Dead Duke, His Secret Wife, and the Missing Corpse: An Extraordinary Edwardian Case of Deception and Intrigue."

In the mid 1800s the Duke created a "black-mouthed" tunnel more than a mile long at Welbeck Abbey so when he arrived via carriage — with its windows blackened — he could slip into his private chamber without being seen. Once inside, if he required a meal or a change of clothes he would place a servants' note to that effect in a brass mailbox outside his door. If his room needed cleaning, he opened a trapdoor in the floor, climbed down a ladder, and waited until the task was complete.

Thomas Druce also kept to himself. He turned up in 1830, taking a job as a lowly London furniture salesman, ascending quickly to partner. He told inquirers he had no mother or father but had simply "sprung from the clouds." His office was completely curtained and employees were not to approach when the curtains were closed. His lover, Annie May, was 30 years his junior and bore him several children before they married, ostracizing them from polite society. A perfect turn of events for such a recluse.

It was Anna Maria Druce, seeking what she believed was her son's rightful inheritance, who set this strange, wordy and exhaustively researched ball of a book rolling. And, sought to open the Duke's coffin lid. It was the men's (man's?) relentless quest for privacy that allowed the mystery of their identity to last nigh unto two centuries. Eventually, the high court had to decide.

" 'Gentlemen,' [the magistrate] said, adjusting his spectacles with a light cough, 'this inquiry may have taken some time, but I do not think any impartial person will say that time has been wasted.' "

I'll not spoil the end, but will offer a caution. Be careful what you tweet. Consider your posts. Doppelgängers await. They could be all in your mind; but they could be outside of it, too.

Mardi Jo Link is the author of five books, including a New York Times bestseller, "Wicked Takes the Witness Stand." She lives in northern Michigan.