Two dress codes: Formal & Elegant Casual (No Jeans).
I spoke with someone who has just returned from a cruise on the QM2 and she was saying many ladies did wear long dresses, but the same amount wore shorter lengths, or even trousers. So, formal does not mean long dresses wear whatever formal attire you feel most pretty in. Most men wore either tuxedo with bow tie or black suit. Jeans were quite acceptable to wear during the day - many people were in them with t-shirts. Since Cunard became part of the Carnival group there slowly have been changes perhaps for the good or perhaps for the bad !!