From William Stukeley onwards the geometry underlying the arrangement of the stones of Stonehenge has lead to many different diagrams, usually with arcs and sometimes with triangles and hexagons.
Quick doodles based on the triangle I deduced from Tim Darvill's work: https://www.sarsen.org/2023/05/ding-dong-over-stonehenge-timekeeping.html has lead me to simple diagram which matches the geometry of the flat faces of the trilithons in the inner horseshoe. It seems different to the historical other diagrams I have seen but I would be surprised if it is new. If you know of a prior example please tell me.
Please excuse a rough diagram:
But you say; "Tim, you endlessly witter on about the middle trilithon and the Altar Stone being at 80 degrees, rather than 90, to the central axis of the monument".
Behold, I respond, if you turn the triangle one gap rather than two it gives a 12 degree twist which is close enough for government work.