I'm writing a story at the moment and am trying to find the age of Gaspard de Chalons...which seems problematic.
I can't find any references to the siblings of Emperor Florian, apart from there were several, and at least two sisters.
This is one toxic family...move over GoT 
Florian had a wife, a male lover, and a mistress (Lady Mantillon, a bard). We have mention that Lady Mantillon had Florian killed, helped Celene disgrace her cousins with stronger claim to the throne, and then to take the throne. We also know that Lady Mantillon trained Celene and to a certain degree Gaspard (though whether before or after Chevalier training is unknown).
According to Word of Gaider, Celene I is 36 in 9:40 our current year, and she is the daughter of the youngest sister of the Emperor Florian.
That would place Gaspard somewhere in the 40-50 range at my best guess.
Does anyone have any more info than that?