A1: First corners cast left shoulder, behind neighbour, cross left shoulder, behind partner to each other's place.
A2: Second corners cast right shoulder, behind partner, cross right shoulder, behind neighbour to each other's place.
B1: (12 bars): All fall back with neighbour (4 small steps); cross right shoulder with partner and immediately face neighbour. Back-to-back neighbour. Back-to-back partner.
B2: Four changes with hands (4 steps for each) (8 bars). Two-hand turn partner.
The way to remember which shoulder to pass is "hug the post" - in other words you want to be close to the person you are about to go round. Particularly useful when you've just changed numbers!