Mr de Bourbon's royal lineage is explained in Le Rajah de Bourbon, meaning The Bourbon Raj, which recounts the swashbuckling adventures of his ancestor Jean-Philippe de Bourbon, a nephew of King Henri IV, who arrived in India in 1560.
He was forced to leave France after a duel and following a series of adventures - involving pirates, slave-traders and Oriental princesses - he arrived in Goa in India, where he became a powerful figure at the Mogul court.
Mr de Bourbon, 48, a jovial father of three, does not live in a chateau befitting a dauphin, but in a simple house in a suburb of Bhopal, the Indian city where his family have lived since 1775.
However, his home is set apart from his neighbours by the brass plaque on the facade bearing an imposing fleur de lys, emblem of French royalty, and the inscription "Maison Bourbon".
The part-time farmer has never been to France and does not speak the language, but his walls are decorated with framed pictures of the Eiffel Tower and the Palace of Versailles, and his children have French names.
According to Prince Michael, who is a member of the Bourbon line, the lawyer is not only the executed Louis XVI's closest living relative, but also a cousin of Prince Philip. He also has the best claim to the lapsed French throne.
"If I am right then Balthazar Bourbon would be the eldest in the line," Prince Michael said.
"This is the cherry on the cake. Mr Bourbon is head of a decent, dignified, middle-class Indian family."
Prince Michael hopes that a DNA test can be carried out, possibly using a lock of Bourbon hair, to prove the claim.
Mr de Bourbon remains modest about the "hypothetical question" of whether he is heir to the throne. "I have always been inculcated with the idea that I belong to a noble and royal family, [but] I am fully aware that France is a democracy," he said, stressing he is not seeking the crown.
"People might believe that I am going to rock the boat because I am Indian. But I am not claiming any riches in France. What counts for me, are the family ties. People must know that a descendent of Jean-Philippe is still alive."
He joked about his family's lost fortune. "Economically, I am the weak link in the family... Bourbons on the rocks."
After a visit from Prince Michael, he is considering making his first trip to Paris. "Daddy was just delighted," said daughter Michelle, 16. "It was the first time he met another Bourbon."
Illustrious ancestry and life on the run
BALTHAZAR Napoleon de Bourbon III can trace his ancestry back to Jean-Philippe de Bourbon, the hot-blooded son of Connetable de Bourbon.
He was the cousin of Henri IV, the first Bourbon king, who came to power in 1589 and was reputed to have more than 60 mistresses and 11 illegitimate children.
According to Prince Michael's historical novel The Bourbon Raj, Jean-Philippe embarked on his swashbuckling adventures after being forced to leave France in the mid-16th century after killing a nobleman during a duel.
He fled to Spain, but found no safe refuge and was kidnapped by pirates.
He then escaped to Egypt, where he was captured once again and sold at the Cairo slave market to the army.
However, he became the protg of the Pacha of Egypt and served in the Ottoman and Ethiopian armies, seducing several Oriental princesses along the way.
He was once again forced to flee, escaping his rivals by travelling to Goa, in India.
There he turned up at the court of the Mogul Emperor Akbar in 1560, marrying his sister-in-law.
He become an Indian raja and founded a long line of Indian Bourbons.
The family settled in Agra and then in Delhi, where Jean-Philippe learned he was the eldest of the Maison de France and next in line to the throne.
However, Jean-Philippe renounced his rights and his descendants moved to Bhopal in 1775, later becoming the region's administrators.