{{explanation}}
2 chords. On 2nd chord 1s+2 also 3s+4s step into Glasgow Highlanders positions

1-8
: 1s+2s also 3s+4s 1/2 turn partners RH into Reels of 4 across ending with
  Men BtoB facing partner
9-16
: 1s+2s also 3s+4s set to partners (in line across) & Ladies set again as
  Men petronella to right, 1s+2s & 3s+4s circle 4H round to left to orig
  places
17-24
: 2s also 3s dance across (passing opposite dancer LSh) & dance down/up
  opposite side, 1/2 turn partner LH & Prom to places (M pass LSh)
25-32
: 1s & 4s repeat bars 17-24 but pass opposite dancers RSh 1/2 turn partner
  RH & Promenade back to places (Ladies passing RSh)
33-40
: All circle 8H round to left 1/2 way, turn partner 2H (moving on) &
  continue circle round to left back to places
41-48
: All set to partners, 1/2 turn RH & dance 1/2 Reel of 4 on sides