They look rather like Pearly Kings,Cockneys who decorated their clothes with pearl buttons.
Some of the clothes were literally smothered in buttons ,but you have to start somewhere!
It would most likely be a parade,for a holiday or Ithink they put a presence in at the racecourses .
They may have been imitating Pearly Kings etc but did not gave as many buttons .Perhaps for an event like King Edward Seventh’s Coronation when there were probably parades and fetes.Viktoria.