Bob Donald, editor of the Ormskirk Memorial Edition, adds the following in the concluding "Notes for Teachers": 

Bars 25-32.  The question posed here is whether in this sequence of changes across the dance, the dancers should slip into place or turn in with a polite turn. The answer is quite unequivocal. The dancers SLIP into place.

The reason is that in this figure, Roy is representing the tacking to and fro of the ship and therefore the line followed by the leading dancers to the foot of the set has sharp changes of direction just as the ship would have.
