The titled nobility of England and Ireland consisted of one rank until 1337, namely that of earl. Edward I (1272–1307) led a restrictive policy on the creation of new earldoms, and at the end of his reign the number of earls was at eleven. The final years of the thirteenth century had seen a dramatic fall-off in the upper level of the nobility, as six earls had died from 1295 to 1298. The earldoms of Hereford and Essex, Hertford and Gloucester, Lancaster, Oxford and Warwick had been filled by 1300, while that of Pembroke had to wait until 1307. Aymer de Valence, 2nd Earl of Pembroke, whose father William died in 1296, did not succeed until his mother's death in 1307, since the earldom descended through the female line of the family. Another great generational change occurred in the years 1306–1307, when six new earls entered the peerage. In addition to Pembroke, the heirs of the earldoms of Arundel, Richmond and Surrey entered into their inheritance. Gilbert de Clare, 7th Earl of Hertford, whose father Gilbert de Clare, 6th Earl of Hertford had died in 1295, was allowed to enter into his patrimony in 1307, after it had been held by his stepfather Ralph de Monthermer, 1st Baron Monthermer for the life of Gilbert's mother. Finally, Piers Gaveston was in 1307 given the earldom of Cornwall, left vacant by the death of Edmund, 2nd Earl of Cornwall in 1300. Of this group, the wealthiest and most powerful was Thomas, 2nd Earl of Lancaster. Thomas was the son of Edmund Crouchback, 1st Earl of Lancaster, who in turn was the son of King Henry III. This made Thomas the nephew of King Edward I, and the cousin of Edward's son Edward II (1307–1327). In addition to the earldom of Lancaster, Thomas was also earl of Leicester and Derby. He was also the son-in-law and heir of Henry de Lacy, 3rd Earl of Lincoln, and at Henry's death in 1311 he succeeded to the earldom of Lincoln as well. Thomas enjoyed a gross income of around £11,000far in excess of the second wealthiest earl, Guy de Beauchamp, 10th Earl of Warwick with about £6,000. At the other end of the scale was Robert de Vere, 6th Earl of Oxford, whose possessions were almost insufficient to uphold the honour of an earldom, but who still maintained his status based on his ancient lineage.