This is a common mistake, causing perplexed and unhappy dancers. Although I have not included any Becket formation contra dances in this set, you may like to know about it in principle. Dancers stand side by side with their partners in two rows, man facing woman. The minor set is with the couple opposite, as usual. Couples at the left-hand ends are neutral for that move.
Couples are now the wrong side of the dance.
If that move is then followed by a normal half right and left with the couple now directly opposite, couples finish up on the correct side of the dance but one place to their left. 1st turn of dance. In the diagonal left and right through, the pairs are ag, bf, ce. Couples d and h will be neutral. The problem about diagonal moves is that the couples at the left-hand ends will not have anybody to work with and often feel unsure of themselves.