Many thanks for the comparison photos Franck. I believe that, in the painting of the marriage of Victoria, the Princess Royal, we can see one of the brooches, worn as a hair comb by the Duchess of Kent.
But which one? I find it difficult to say, as we are looking at a painting, not a photo. It could even be another one which we have not yet seen -- as media reports indicate that the Duchess had several "bouquets"
I also think that the Duchess was wearing two of the brooches as a corsage ornament for the christening of Edward VII.