Source: A 1794 dance, contributed by Nibs Matthews from Ralph Page; published in English Dance & Song, Summer 1966, Volume XXVIII No. 3
Formation: Longways; Triple Minor; Proper
Grimstock Hey: #1s split the #2s to start Heys on the Side
#1s Lead Down, Turn Alone
Lead Up, (Assisted) Cast into 2nd Place
All Six Circle Left
#1s & #2s (Eyes-Only) Right & Left Through x2
Music: 32 bars.
Notes: The article suggests that #1s both start the Hey with right shoulders, but that means that, at the end of the Hey, #1 Lady is heading the wrong way for the next move. It is far smoother for #1 Lady if you dance a Mirror Hey, both starting down the middle. This is indeed the way it is danced in this video:
It is unlikely that the 1794 document specified how the Hey should start.
The Right & Left Through is a same-gender one, sometimes called Eyes-Only. The same video shows the current American style for dancing this sort of move (ignoring the error by one couple on the second Right & Left Through in the first time through the dance!). Both dancers follow the path of a normal Right & Left Through, but with no contact, the left hand dancer moving backwards. The move is sometimes done with arms around each other instead, as in the assisted cast that they do in the video. The original instruction was likely to just be "rights & lefts"; this is a modern American interpretation. For more information see Rights & Lefts.