The painting, depicting the 1654 ceremony, had hung in Rokeby Park, Barnard Castle, since 1880, according to its owner Sir Andrew Morritt.
But it became damaged. Now after being restored, Sir Andrew is trying to find out how it ended up in Durham.
Experts have studied it, but do not know who painted it.
It has also not yet been valued.
Sir Andrew said: "What is a mystery is when it came and where it came from, or who it was painted by.
"All I know for a fact is it has been here since at least 1880, and probably longer."
Veronique Gerard-Powell, chief curator and senior lecturer at the Sorbonne, in Paris, said: "This is the only painted representation of the coronation. There is no other like it - it really is quite unique."
Rokeby Park, which was built between 1725 and 1735, has hundreds of valuable paintings, according to Sir Andrew.
A country house owner is trying to find out how the only known painting of the coronation of the French king Louis XIV end up in his stables.