The same archaeologists, who excavated the grave of Richard III, have found a lead coffin within a stone casket in the same car park of the previous discovery. You can see pics here and here. The Huffington Post article has a slideslow of the discovery and excavation. Ancient Rome and early Christians had traditions of nesting coffins within stone Sarcophagi. These were reserved for the high-ranking and rich ley people, and church leaders.
This team of researchers will proceed carefully when opening the lead coffin to prevent damage to any remains inside. The top candidates for the individual buried inside are: Sir William de Moton of Peckleton, a knight; or two of the high status friars of the English Grey Friars order, Peter Swynsfeld, and William of Nottingham.