It turns out that they were a Unitarian semi-monastic order in the that formed 1970s and 80s for the purpose of developing liturgy and deepening spiritual practice. This was at the height of the influence of secular humanism in the UUA. Their liturgy drew a lot from Benedictine Catholic & Buddhist sources. Apparently they published a Book of Hours in 1985, probably a pretty limited run- I can't find it. I'm going to ask around at Unity especially the Library Team to see if I can find out more about them. I think the UUs could still really use a group like that!
On a side note, I also wondered about the name "Abraxas" It sounded to me to be vaguely Greek and ceremonial magicky- I was kind of right it goes back to Gnosticism- the history of it is rather complex!