She used a photo finishing powder but apparently it wasn’t applied well and evenly with a brush.
Otherwise she cut an elegant figure. So much better carriage and bearing than the current WH.
Even with the face powder, she looks better than ours............................
It doesn’t really matter how it was applied, although it looks like a puff was used. Even with a brush, it would still have flashback. A very thin layer would allow less reflection, though you’d still get it depending on the ingredients. The only way to be sure powder won’t overly reflect under flash is to pretest it.