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

1-4
: 1s cross down **while** 4s cross up, 1M+4L also 1L+4M in prom hold dance
  out to right & into centre facing own partner
5-8
: 1s & 4s change places RH with partner & chase round inside clockwise to
  end 1s in 2nd place opposite sides & 4s in 3rd place own sides
9-12
: 2s cross down **while** 3s cross up, 2M+3L also 2L+3M in prom hold dance
  out to left & into centre facing own partner
13-16
: 2s & 3s change places LH with partner & chase round inside anticlockwise
  to end 2s in 2nd place opp sides & 3s in 3rd place own sides.
  (1)(2) 3 4
17-24
: 1s+2s Set+Link, 1s+3s set & dance RH across 1/2 way
25-32
: 1s+4s Set+Link, all set & cross RH.  2 3(4)(1)