{{explanation}}
2 Ch - 1M stand as 1L crosses to 2M pl who crosses to ptnrs pl, 2L steps up

1-8
: 1s+2s dance R&L ending with 2M between 1L+2L facing down 1M directly
  behind 2M
9-16
: All dance down middle, turn right about & 1M dances Ladies back to top
  (2M follows) to form a line 4 across with Men BtoB facing partners
17-24
: All set to partners with suitable step
25-32
: All dance reel of 4 across ending in new pstns with each couple having
  moved 1 place anticlockwise round set

: On bars 31/32 3M crosses to partners place as 3L steps up to start next
  32 bars

: Similarly on bars 31/32 (2nd time through) 4M crosses to partners places
  as 4L steps up