white with a black arm-band
...and I did get a little wicked laugh watching the republican dragoon fall of his horse in the march to the Arch of Triumph. However, though I realize why it is done etc, etc, it still annoys me that other monarchs take part or have their people take part in celebrating such a thing. A year or two ago the (Bourbon!!) King of Spain was present and this year I saw some of Her Majesty's redcoats taking part in the parade. Ah well, c'est l'politique.
Vive le Roi!