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

1-8
: 1s & 4s dance into centre of set (others move down/up) & PdB Coupe once,
  circle 4H round to left & end facing corner persons
9-16
: 1s & 4s set to corners & change places LH, corners dance RH across & end
  in prom hold facing 'own' end of set
17-24
: 1s+2s also 4s+3s dance RSh reels of 3 across set (going right) & 2s & 3s
  end in 1st/4th places **while** 1s & 4s curve round into centre to
  face each other (1s facing down)
25-32
: 1s+4s dance Men's Chain passing partner with RH
33-40
: All circle 8H round & back