De la More gravitated into the service of Richard Neville, Earl of Salisbury by 1452, and perhaps as early as the previous decade. Within a few years, Salisbury's sons became engaged in a bitter feud with those of the Earl of Northumberland, led by Thomas Percy, Lord Egremont. At the same time, the King was mentally incapacitated and unable to govern. The House of Lords had appointed the Duke of York protector during the King's illness, and York, in turn, made Salisbury his Lord Chancellor. Following the Yorkist victory at the First Battle of St Albans, York held another parliament towards the end of the year, and another general pardon was issued which de la More again took advantage of on 10 October 1455. Both of de la More's pardons, suggests Rawcliffe, were "no doubt to cover himself from charges of malpractice in office". In the latter document, he is listed as "of Comberkath, Cumberland, esq., "alias" gent., "alias" late of London". Wedgwood speculates that the latter designation may have been the result of de la More's attendance at the York's parliament between 1455 and 1456.