Complex sentence: Mary Arundell died in London, and was buried at the church of St Clement Danes, although a lead coffin claimed to contain her remains was found at Arundel Castle in 1847 and was placed under the Fitzalan chapel there.
Split into simpler sentences: Mary Arundell died in London, and was buried at the church of St Clement Danes. A lead coffin, said to contain her remains, was found at Arundel Castle in 1847, and is now buried beneath the floor of the Fitzalan chapel there.