Osthrith, however, seems to have been unpopular among the Mercians. She had a great devotion to her uncle, St. Oswald of Northumbria, and desired to lay his bones in her husband's noble monastery at Bardney in Lincolnshire. The monks objected, because St. Oswald had warred against Mercia and reigned over it as a foreign king. When, one evening, a wagon arrived at Bardney, bearing the good king's body, they would not open their gates. So the cart was left, all night, outside the monastery. No sooner was it dark, than a wondrous light emanated from the bier and was seen for miles around by all the dwellers in the province. A pillar of glorious light stood over the saint's body, reaching up to heaven. In the morning, the monks, who had wished to send the relics back to Northumberland, were, of course, now eager to have the Royal saint buried in their church.

On 5th August AD 697, a rebellious faction in Mercia murdered poor Osthrith. She was buried at Bardney and, seven years later, Aethelred decided to resign his throne to Coenred, the son of his elder brother, Wulfhere, and St. Ermengilda, and became a monk in the same monastery. He died there, in AD 715, and was buried beside his wife. They left a son, Coelred, married St. Werburga of Mercia, who, in AD 709, succeeded his cousin, Coenred to the throne of Mercia.