Cecily Neville was a daughter of Ralph Neville, 1st Earl of Westmorland, and Joan Beaufort, Countess of Westmorland. Her paternal grandparents were John Neville, 3rd Baron Neville de Raby and Hon. Maud Percy, daughter of Henry de Percy, 2nd Baron Percy. Her maternal grandparents were John of Gaunt, 1st Duke of Lancaster, and Katherine Swynford. John of Gaunt was the third surviving son of Edward III of England and Philippa of Hainault. By her mother, Cecily was a niece of King Henry IV of England.  She was the aunt of Richard Neville, 16th Earl of Warwick, one of the leading peers and military commanders of his generation, a grand-aunt of queen consort Anne Neville, and a great-great-grand-aunt of queen consort Catherine Parr, sixth wife of her great-grandson, King Henry VIII.  In 1424, when Cecily was nine years old, she was betrothed by her father to his thirteen-year-old ward, Richard Plantagenet, 3rd Duke of York. Ralph Neville died in October 1425, bequeathing the wardship of Richard to his widow, Joan Beaufort. Cecily and Richard were married by October 1429. Their daughter Anne was born in August 1439 in Northamptonshire. When Richard became a king’s lieutenant and governor general of France in 1441 and moved to Rouen, Cecily moved with him. Their son Henry was born in February but died soon after.

Their next son, and the future King, Edward IV was born in Rouen on 28 April 1442 and immediately baptised privately in a small side chapel. He would later be accused of illegitimacy directly by his cousin, Richard Neville, 16th Earl of Warwick, and by his own brother, George, Duke of Clarence; this was a common method of discrediting political enemies, and George and Warwick were in dispute with Edward at the time and seeking to overthrow him. The claims would later be dismissed. Nonetheless, some modern historians give serious consideration to the question, and use Edward’s date of birth as supporting evidence: assuming Edward was not premature (there being no evidence either way), Richard of York would have been several days’ march from Cecily at the time of conception and the baby’s baptism was a simple and private affair (unlike that of his younger brother, Edmund, which was public and lavish). This is countered by other historians, however, who point out that Cecily’s husband could easily, by the military conventions of the time, have returned briefly to Rouen, where Cecily was living at the time, whilst baptism conventions of the time meant that a low-key baptism would be more likely due to Richard of York’s political standing at the time vis-a-vis his later position, and fears for the baby’s survival; if the difference in baptisms was to be taken as a disavowal of an otherwise acknowledged and cherished heir, it would not only be a humiliation of a wife Richard otherwise valued before and after Edward’s birth, but also a personal and political humiliation. In any case, Richard acknowledged the baby as his own, which established legal paternity.  Around 1454, when Richard began to resent the influence of Edmund Beaufort, 1st Duke of Somerset (a first cousin of Cecily’s), Cecily spoke with Queen consort Margaret of Anjou on his behalf. When Henry VI suffered a nervous breakdown later in the year, Richard of York established himself as a Protector.

After the outbreak of the Wars of the Roses, Cecily remained at their home, Ludlow Castle, even when Richard fled to Ireland and Continental Europe. At the same time she surreptitiously worked for the cause of the House of York. When a parliament began to debate the fate of the Duke of York and his supporters in November 1459, Cecily travelled to London to plead for her husband. One contemporary commentator stated that she had reputedly convinced the king to promise a pardon if the Duke would appear in the parliament in eight days. This failed and Richard’s lands were confiscated, but Cecily managed to gain an annual grant of £600 to support her and her children.  After the Yorkist victory at the Battle of Northampton in July 1460, Cecily moved to London with her children and lived with John Paston. She carried the royal arms before Richard in triumph in London in September. When the Duke of York and his heirs officially recognised as Henry VI’s successors in the Act of Accord, Cecily became a queen-in-waiting and even received a copy of the English chronicle from the chronicler John Hardyng.  In the Battle of Wakefield (30 December 1460), the Lancastrians won a decisive victory. The Duke of York, his second son Edmund, Earl of Rutland, and Cecily’s brother Richard Neville, Earl of Salisbury, were among the casualties. Cecily sent her two youngest sons, George and Richard, to the court of Philip III, Duke of Burgundy. This forced Philip to ally with the Yorkists.

Her eldest son Edward successfully continued the fight against the Lancastrians. When Cecily moved to Baynard’s Castle in London, it became the Yorkist headquarters and when Edward defeated the Lancastrians, she became an effective Queen Mother.  During the beginning of Edward’s reign, Cecily appeared beside him and maintained her influence. In 1461 she revised her coat of arms to include the royal arms of England, hinting that her husband had been a rightful king. When Edward married Elizabeth Woodville, he built new queen’s quarters for her and let his mother remain in the queen’s quarters in which she had been living.  In 1469, her nephew, the Earl of Warwick, father-in-law of her sons George and Richard, rebelled against Edward IV. Warwick also began to spread rumours that the king was a bastard and that his true father was not the Duke of York but an archer named Blaybourne at Rouen, evidence of which has been assembled. By some interpretations, that would have meant that Clarence was the rightful king. Warwick had earlier made similar accusations against Margaret of Anjou. Cecily said little about the matter in public, despite the fact that she had been accused of adultery. She visited Sandwich, possibly trying to reconcile the parties. When the rebellion failed the first time, she invited Edward and George to London to reconcile them. Peace did not last long and in the forthcoming war she still tried to make peace between her sons.

Edward IV was briefly overthrown by Warwick and Margaret of Anjou, and for about six months (October 1470 – April 1471) Henry VI was restored to the throne. The breach between Edward and his brother George was apparently never really healed, for George was executed for treason in the Tower of London on 18 February 1478. Edward IV died suddenly on 9 April 1483, leaving two sons aged 13 and 10. Cecily Neville’s youngest son Richard, their uncle, was appointed their protector by Edward’s will, but he had them placed in the Tower, whence they were never to emerge; their subsequent fate is a matter of dispute. A subsequent ‘enquiry’ found that that Edward IV’s marriage to Elizabeth Woodville had been invalid: their children were thus pronounced illegitimate, making Richard the legal heir to the crown. The Princes in the Tower were declared illegitimate by Act of Parliament in 1483 to allow their uncle Richard to be crowned Richard III on 6 July 1483.  Duchess Cecily was on good terms with Richard’s wife Lady Anne Neville (her grandniece), with whom she discussed religious works such as the writings of Mechtilde of Hackeborn.  Richard’s reign was brief, as he was defeated and killed on 22 August 1485 at the Battle of Bosworth by the last Lancastrian, Henry Tudor. Thus by 1485, Cecily’s husband and four sons had all died, although two of her daughters, Elizabeth and Margaret, still lived. On 18 January 1486, Cecily’s granddaughter, Elizabeth of York, eldest daughter of Edward IV, married Henry VII and became Queen of England. Cecily devoted herself to religious duties and her reputation for piety comes from this period.

Duchess Cecily died on 31 May 1495 and was buried in the tomb with her husband Richard and their son Edmund at the Church of St Mary and All Saints, Fotheringhay, Northamptonshire, with a papal indulgence. All subsequent English monarchs, beginning with Henry VIII, are descendants of Elizabeth of York, and therefore of Cecily Neville.  “Cecill wif unto the right noble Prince Richard late Duke of Yorke” made her will on 1 April 1495. It was proved at the Prerogative Court of Canterbury on 27 August of the same year.