Who is the poor chap in the sailor suit?!
The was child on the balcony last year in the same outfit. Can't find a picture in RD that shows the full cohort of royals on the balcony from 2016.
Here's last year's picture on the balcony with boy in the sailor suit.
Perhaps the answer to the question...
Friend who keeps much closer track of these things than I ever will believes the boy in the sailor suit is Albert Windsor. Boy next to him, his older brother.
Albert Windsor, born 2007, son of Lord Nicholas Windsor (sister of Lady Helen Taylor)
Older brother: Leopold Windsor, born 2009. They have a younger brother named Louis born 2014.
So....perhaps the answer to the question.
The one with the suit is brunette and all the Windsor brothers are blonde but the boy with the sailor suit kind of looks like the eldest one, Leopold.