Mystery of History

Could this fragment of pottery be from the privy pot of Mary Queen of Scots? Found on the shore below Blackness Castle.
I think from the lack of barnacles that it probably isn't very old. Still wonder what the text says. Is it part of a poem perhaps?
Took it to one of the castle guides who didn't seem bothered and said to keep it if I wanted. Next step Antiques roadshow!

Extras of the castle