This is a cobalt bue blazer style pleat dress. It is double breasted with a big collar, pleats at the waist and it is fastened at the front with a double row of buttons.
This dress has a nice colour but the bodice looks a bit ill-fitting. It was first worn by her mother Carole Middleton.
1- The Duchess of Cambridge wore it for her first public address at The Treehouse children’s hospice, Ipswich on 19th March 2012.