Cecily's life after the death of her first husband in 1501 was marked by an acrimonious dispute with her son and heir, Thomas Grey, 2nd Marquess of Dorset.

This was over Cecily's right to remain sole executor of her late husband's estate and to control her own inheritance, both of which Thomas challenged following her second marriage to Henry Stafford; a man many years her junior.

The Bonvilles, having fought with the Yorkist contingent, were shown no mercy from the victorious troops of Margaret of Anjou (wife of King Henry VI of England), who headed the Lancastrian faction, and were thus swiftly decapitated on the battlefield.

[6] These executions left Cecily Bonville as the wealthiest heiress in England,[7][8] having inherited numerous estates in the West Country,[9] as well as manors in Lancashire, Lincolnshire, Yorkshire, and Cumberland.

Warwick turned his offer down, as he considered the Earl's son to have been lacking in sufficient noble birth and prestige to marry a member of his family.

He was the eldest son of King Edward's queen consort, Elizabeth Woodville, by her first husband, Sir John Grey of Groby (a Lancastrian knight who had been killed in combat at the Second Battle of St. Albans, the site of Cecily's great-grandfather's execution).

At the time of Cecily's marriage to Thomas, the latter held the title of Earl of Huntingdon; he resigned this peerage a year later in 1475, when he was created Marquess of Dorset.

In this position of authority, Richard had gathered a force of friends, local gentry and retainers, headed south in an armed cavalcade from his Yorkshire stronghold of Middleham Castle to take into protective custody and separate the young king from the Woodvilles, putting a prompt end to their ambitions and long dominion at court.

Richard's claim was supported by an Act of Parliament known as Titulus Regius which declared Thomas's half-brother the uncrowned King Edward V and his siblings illegitimate.

During the time Thomas remained abroad in the service of Henry Tudor, King Richard ensured that Cecily and the other rebels' wives were not molested, nor their personal property rights tampered with.

The following month, the new king lifted the attainder which had been placed on Thomas in January 1484 by Richard III for his participation in the Duke of Buckingham's unsuccessful rebellion.

[30] In the 1490s Cecily added a magnificent fan vaulted north aisle, which she had personally designed, to the Church of Ottery St Mary in Devon.

She also made several additions to other churches situated within the locality of her vast West Country holdings; however, none were executed as splendidly, and with such meticulous attention to detail as the Dorset Aisle.

Her son Thomas, the 2nd Marquess of Dorset vehemently disapproved of the match, as it is alleged he feared she would use her inheritance to "endow her new husband at his own expense".

[35] His fears did have some foundation as Cecily gave Stafford a life estate in holdings valued at £1,000 per year and even vowed to leave him the remainder of her capital should Thomas happen to predecease her.

[36] This provoked Thomas to challenge Cecily's right to continue as his father's sole executor, resulting in an acrimonious dispute that necessitated the intervention of King Henry VII and his council to stop it from escalating even further.

[37] The settlement the King decreed allowed Cecily to manage her late husband's estate until she had paid off his debts, but prevented her from claiming her dower until she had transferred the remainder of her son's inheritance to him.

[37] King Henry's arbitrary decision also severely limited her control over her own inheritance: she was required to bequeath all of it to Thomas upon her death; until then, Cecily was permitted to grant lands worth up to 1,000 marks per annum for a certain number of years.

[37] Historian Barbara Jean Harris stated that the Crown's oppressive decree greatly restricted Cecily's personal rights as an heiress in favour of those of her eldest son and the tradition of primogeniture.

She was buried in the Collegiate Church of St. Mary the Virgin, Astley, Warwickshire, where her effigy (which has been damaged), can be seen alongside those of her distant cousin, Sir Edward Grey, Viscount Lisle (d. 1492) and his wife Elizabeth, née Talbot (d. 1487).

[45] In February 1537, her daughter Cecily Sutton wrote to Henry VIII's chief minister, Thomas Cromwell, complaining of the poverty in which she and her husband were forced to live.