Margaret Pole (neé Plantagenet) was the Countess of Salisbury and, for a time, also the godmother and Governess of Princess Mary Tudor.
Margaret is a devout Catholic and a member of the House of York, which fought Henry's father during the War of the Roses; she is first cousin of Henry's mother Queen Elizabeth of York through her father George Plantagenet, Elizabeth's uncle and the brother of Edward IV. Because of this, she becomes an unprovoked target for the King's anger.
In episode 3.03 the Countess of Salisbury came to count at the Christmas holiday. After Jane helps Henry reconcile with his daughter Mary, she asked her father if he remember her former Governess? Margaret Pole and king Henry VIII rekindled their family bond. Even came to terms for her son Reginald and his scholarly life. For the moment having the king’s forgiveness.
When her son Reginald Pole, a priest living in exile in Rome, begins denouncing Henry's Protestant government (3.04) and imploring Catholic powers to invade England. Unable to reach Reginald, (episode 3.05) Henry instead takes out his vengeance against Margaret, her other son, Henry Pole (the Lord Montague), and her young grandson, by having Sir Francis Bryan arrest them.
They are cruelly beheaded (3.06)
This character is loosely based on a woman of the same name; Margaret Pole, the 8th Countess of Salisbury, was appointed Governess of the Princess Mary Tudor and her Household. Her eldest son, Henry Pole, Baron Montagu, another son and other relatives were arrested on a charge of treason, though Sir Thomas Cromwell, Earl of Essex had previously written that they had "little offended save that he [the Cardinal] is of their kin". With the exception of Geoffrey Pole, they were all executed. Ten days after the arrest of her sons, Margaret herself, despite her age, was arrested and examined but would "nothing utter". Because of the popularity of the Countess,Henry stayed the inevitable penalty of death, which eventually came in May of 1541.
According to some accounts, the countess, who was 67 years old, frail and ill, was dragged to the block, but refused to lay her head on it, having to be forced down. As she struggled, the inexperienced executioner's first blow made a gash in her shoulder rather than her neck.