The vellum has been shown in the House of Lords." {31} ".

.

.

The ring was taken off Mary's finger by a man in anger and jealousy: he threw it into the water.

When he took it off, she was being carried in a kind of bed with curtains" (a litter).
Just before Rizzio's murder Mary was enceinte, and might well be carried in a litter, though she usually rode.
The seer then had a view of Sizzle's murder, which he had probably read about.
Three weeks later, in another trance, the seer finished his design of the vellum.