She took the cape thing off for the inside event and the dress underneath is the one she wore for the Christmas carol service that she also has in black which she wore for Prince Phillip's funeral. I was trying to work out if the bow is an extra one on the cape or whether it is detachable and added to the outside and then back on the dress, or if it is pulled through the front of the cape.
She's obviously had the cape made to go with the dress, someone on Instagram was speculating that its shape is a tribute to traditional Korean hanbok dress - which it might be because that's an odd silhouette too.
I thought the Korean First Lady looked lovely too - must be hard being the spouse who has to stand next to Kate and be compared dress for dress at all these events.