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

1-8
: 1s & 4s petronella turn to centre, turning RH dance out of ends & cast
  down/up to 2nd/3rd places on original sides
9-16
: 1L+4M also 1M+4L in prom hold dance LSh reel of 3 with 2s/3s
17-24
: 1s & 4s dance up/down between 2s/3s & cast down/up to 2nd/3rd
  place, 1s+4s 1/2 R&L
25-32
: All dance reel of 4 on sides.  2 4(1)(3)