The French conductor discusses unearthing the Sun King’s finest hour and how too many cooks didn’t spoil this particular broth.

Congratulations on winning our Opera Recording of the Year. Le Concert Royal de la Nuit was the famous occasion when the young Louis XIV danced the role of Apollo and became known ever after as the Sun King. How come we’ve never heard the music before and how did your reconstruction come about?

The idea came after I read a score that I had known about for a long time at the French Library. It’s a work of legend, because we know from the history books that this happened in 1653. This event was mentioned many times by historians, but each time I saw the score I was thinking “Oh, what a pity, we have only four vocal lines and we have a lot of music but only maybe five percent [is complete]. Each time I read this book I thought what a pity, until the moment I really read the vocal music and thought “It’s really incredible – I want to try to reconstruct the whole thing!”. It’s a strange thing, because it’s not a sudden discovery. I...