Complex sentence: Twenty-three surviving portrait miniatures are usually attributed to Horenbout, all but one, a portrait of Holbein, of members of the English or other royal families; paintings of at least four of Henry's Queens are attributed to him.
Split into simpler sentences: Twenty-three surviving portrait miniatures are usually attributed to Horenbout; all but one, a portrait of Holbein, are of members of the English or other royal families. Paintings of at least four of Henry's Queens are attributed to him.