I found this McCalls dress pattern from the 1950's that has a very similar look to it.
I have seen many predictions among the vintage community about what the dress will look like and I have to say that most the predictions I have seen were right on the money. Covered shoulders and a chapel length train check check I love how on the money these predictions are. My son as we watch this wedding wants to know if they don't do "you may now kiss the bride". My son has a teacher from Plymouth on a Fulbright exchange so he has been hearing lots about the Royal Wedding (I am guessing more than most American 9 year old boys do). In fact my son is having a royal wedding party in his 3rd grade classroom today. The kids have been encouraged to dress up but he said he would prefer not to but would like to wear his Mohawk up.