Cecily was the third-born daughter of Elizabeth Woodville and King Edward IV, but her older sister Mary died when she was aged only fourteen, making Cecily the second daughter after Elizabeth of York.
In 1474, Cecily was betrothed to the son of James III of Scotland. This was very unpopular, and did not go ahead. In 1482, a further marriage for Cecily was considered, this time to the Duke of Albany, who had recently allied himself to Cecily's father. The Duke of Albany had ambitions of acquiring the Scottish throne for himself, but he did not achieve this aim and he died before a marriage to Cecily could take place.
The first man that Cecily actually married was Ralph Scrope of Upsall, a supporter of the new usurping King Richard III. However, this marriage was annulled when Henry VII beat Richard III at the battle of Bosworth in 1485 and took the English throne.
In 1487 Henry VII married Cecily's elder sister, Elizabeth of York. This was a tactical move by Henry VII as his marriage united the warring houses of York and Lancaster, and ended the Wars of the Roses. Cecily was also married to a Lancastrian, Viscount Welles. Welles was half-uncle to Henry VII (being a half-brother to Henry's mother, Margaret Beaufort), and was a favourite at his court. Cecily's marriage to Welles produced three children, but only one, Robert, survived to adulthood. Welles died in 1499, and Cecily's grief at his passing was said to be considerable.
Cecily married again for a final time to Thomas Kyme. As Kyme was not well known at court, it is possible that Cecily married him for love, not for politics. Their marriage took place in 1502, without King Henry VII's permission. When the King found out about the marriage he banished Cecily from court and confiscated her estates. Cecily lived out her final years away from court. She may have had children with Kyme in these final years, but as they did not inherit her estates information about them is scarce. Cecily died aged 38 in 1507.
From The White Princess
Cecily makes a sulky face. In the last weeks, before Richard the king rode out to battle, he ordered her to be married to Ralph Scrope, a next-to-nobody, to make sure that Henry Tudor could not claim her as a second choice of bride, after me.
Cecily, like me, is a princess of York, marriage to any of us gives a man a claim to the throne. The shine was taken off me when gossip said that I was Richard’s lover, and Richard demeaned Cecily too by putting her in a lowly marriage.
She claims now that it was never consummated, now she says that she does not regard it, that Mother will have it annulled; but presumably she is Lady Scrope, the wife of a defeated Yorkist, and when we are restored to our royal titles and become Princesses again, she will have to retain his name and her humiliation even if no-one knows where Ralph Scrope is today.