Chalice at heart of mystery involving two murdered priests in Cork now held in British museum

The Mount Keefe Chalice Chalice. Picture: Victoria and Albert Museum 

One of Ireland's oldest religious artefacts is at the centre of a mystery involving the murder of two priests in Co Cork.

The Mount Keefe Chalice is believed to have been used by the priests when they celebrated Mass in around the 1690s, during the Penal Laws that outlawed Catholic Masses.