{{explanation}}
3s & 4s start on opp sides

1-8
: 1s & 4s set & cross RH, cast in 1 place & 1M+4M petronella turn into
  centre **while** partners turn LH to end BtoB facing partners
9-16
: 1s+4s dance reel of 4 in centre
17-24
: 1M followed by partner dance reel of 3 with 2s (RSh to 2L) **while** 4M
  followed by partner reel of 3 with 3s (RSh to 3L) & end 2(1)4(3)
25-32
: 1s+4s dance RH across, 1s+4s set facing & change places RH on sides to
  end 2 4(1)(3)