Kate wore the gown (with a diamond tiara that once belonged to her late mother-in-law, Princess Diana) for a state banquet hosted at Buckingham Palace.
The mum-of-three attended the dinner, hosted by Queen Elizabeth II in honour of King Willem-Alexander and Queen Maxima of the Netherlands, with husband Prince William and a number of other senior royal family members.
But all eyes were on Kate's Alexander McQueen dress, which has been the point of backlash among many.
Etiquette expert William Hanson Tweeted: “Who even needs to iron these days?”
Another person said: “So glad to see Kate wearing the Royal Family Order of the Queen for the first time, but sorry really not liking the dress at all.”
Many also pointed out that it looked like a prom dress from the '80s.
