My bad, I thought it was a different spelling of the old Fleur.
My bet is on an anachronistic mistake with the flag, happens all the time. It is in style of historical regimental flags, but I think a research error is more likely than it being the actual regimental flag. There won’t have been many special royal (with Fleur de Lys) regiments, so it would surprise me if we couldn’t easily find that particular flag.
Thanks for the thorough research! Considering it was painted quite recently my guess was also a simple mistake. I was really surprise seeing the flag used is such a historical context
My bad, I thought it was a different spelling of the old Fleur.
My bet is on an anachronistic mistake with the flag, happens all the time. It is in style of historical regimental flags, but I think a research error is more likely than it being the actual regimental flag. There won’t have been many special royal (with Fleur de Lys) regiments, so it would surprise me if we couldn’t easily find that particular flag.
A historical chart of regimental flags, made in 1771, with the year that each flag was created: http://web.archive.org/web/20071028170126/http://www.cg78.fr/archives/img/db/seriea/hd/sa00110.jpg
An article on those flags and others: https://www.crwflags.com/fotw/flags/fr^r_mon.html
Plenty of white crosses, plenty of Fleur de Lys, but no flag that is a proper match…
The closest I get is this family coat of arms, which is probably more a coincidence than anything else: https://man8rove.com/fr/blason/dzcmzn9-desmier-alias-desmiers-alias-dexmier
Thanks for the thorough research! Considering it was painted quite recently my guess was also a simple mistake. I was really surprise seeing the flag used is such a historical context