This dance was significantly modified, in agreement with the deviser, from the version first sent in, to the version published.   
It is said the deviser would have preferred to omit the setting on [17-18], which makes it necessary to deviate from standard phrasing on [17-28].  
On [20-21] 1c leads down, crossing back to own side.  It would seem that a LH lead would be more convenient than the traditional RH version.  The original instructions give no information on this.   