Julian Cope presents Head Heritage

I've often wondered if the joint was craftily chosen - to allow a bit of lateral "give" if (for instance) some additional weighting was placed on or against the lintols.

In addition, rounded/tapered stub tenons might make it a lot easier to slot the whole ring together (allowing a degree of jiggling of the supporting uprights until everything fitted) - quite a consideration when you're trying to assemble a ring weighing scores of tons high in the air! After all, it might form a nice neat ring when laid on the ground but become a bit of a problem when you tried to erect it. It's the MFI flatpack syndrome....

I might be wrong about that but I haven't seen a queue of experimental archaeologists anxiously waiting to replicate that bit - even six inches off the ground!