It matches closely with known typologies of rings (particularly of stirrup-shaped type) from the period of the 14th to 15th centuries. Also the Black Letter script helps date it to this period too.

And yep, the ring was reported and recorded as part of the UK's Treasure legislation and recorded by the local Finds Liaison Officer. The issue may have been that a museum was interested in acquiring the object, BUT the Treasure Valuation Committee price was too high and the museum pulled out, thus meaning the object was then disclaimed and returned to the finder.