{{explanation}}
3s and 4s start on opposite sides

1-8
: 1s+4s cross RH, cast to 2nd/3rd places, 1s+4s dance LH across remaining
  in middle with 1s facing 2s, 3s facing 4s
9-12
: 1s+2s also 3s+4s turn RH once round. 1s+4s in middle chase
  anticlockwise 1 place round to finish BtoB in centre with1s facing
  Men's side, 4s facing Ladies' side
13-16
: 1s+4s set to corners and partner (as "Hello-Goodbye") to finish BtoB in
  centre with 4s facing up, 1s facing down
17-28
: All dance Interlocking diagonal reels of 4 giving LH across in centre.
  Finish as end bar 16
29-36
: 1s+4s dance RSh round "corner" into centre, dance RH across, retain
  ptnr's hand with 1s turning to face down/ 4s face up
37-40
: 1s+4s cross out of ends and cast up/down to finish 2 4 (1) (3)
41-48
: All turn partner RH, all circle 8H round 1/2 way to finish 3 1 (4) (2)