The Howard family line at Folkingham ended on 2nd June 1572 when Thomas Howard, 4th Duke of Norfolk was executed, having been attainted of high treason for his involvement (for which he was probably innocent) in the Ridolfi Plot of 1571. The plan was to assassinate Queen Elizabeth I of England, who was a Protestant, and replace her with her first cousin once removed, Mary, Queen of Scots, restoring Catholicism in England. The 4th Duke of Norfolk was Elizabeth’s cousin, and by now the wealthiest landowner in the country, and had been proposed as a possible husband to Mary since her imprisonment in 1568. This suited him as he was very ambitious, and felt that Elizabeth persistently undervalued him. He had previously become involved in the Northern Rebellion of 1569, until he lost his nerve. In any event, the two plots both involved Catholics, and Norfolk remained a Protestant until the day he was beheaded on Tower Hill in London.Gilbert de Gant died in Folkingham in 1095, but the family continued to live here. By the early 13th Century, a stone keep had been added, but this seems to have been damaged during the Barons’ rebellion against King John in 1216. However, by 1219, rebuilding in stone was well under way.
The Gant, or Gaunt line died out in 1298, the estates reverting to the Crown. King Edward I then granted the estates to his cousin Henry de Beaumont.
The castle was rebuilt in 1321 by Henry, Baron de Beaumont, after Henry obtained permission from the King to embattle and fortify it, effectively obtaining a licence to defend his house. The castle was now a formidable fortress standing on a rectangular island with a Gatehouse to the West, a strong curtain, and both inner and outer moats. The moat enclosed an area of about 10 acres. To the North was another earthwork, rectangular in shape and with a pond at one end. It may have been a garden or orchard. King Edward III came to inspect the castle on 17th August 1331, and stayed on until the 19th August, when he moved on to Heckington. The castle was occupied by the Beaumont family for almost 200 years.
On 8th November 1448, John Viscount Beaumont was given permission to have his own gaol in the castle. In 1471, during the Wars of the Roses, his son William de Beaumont, Lord Bardolf, fought on the Lancastrian side against King Edward IV who led the Yorkist cause, at the battle of Barnet, and was declared a traitor. After the end of the Wars, he had to buy his pardon from Henry VII for the enormous sum of £10,000, but in 1487, was reported to have “lost his reason”; and the custody of his lands (and from 1495 the custody of his person) was committed to John de Vere, the Earl of Oxford, who later married William’s widow Elizabeth Beaumont.
As the de Beaumont line failed in 1507, the Manor again reverted to the Crown, then granted to Thomas Howard, 3rd Duke of Norfolk.
In 1535, it was reported that Folkingham castle was already falling into disrepair. The Dissolution of the Monasteries by Henry VIII between 1536 and 1541 resulted in hordes of out of work monks roaming the country, begging.
In 1546, Thomas Howard was attainted; or accused, of concealing the high treason of his son Henry Howard, Earl of Surrey who was executed for assuming the royal arms of Edward the Confessor. The 3rd Duke of Norfolk offered his lands to the dying King, Henry VIII, and his life was spared, but he remained incarcerated in the Tower of London throughout the succeeding Edward VI’s reign.
His lands however, were dispersed by the ruling clique during the short reign of the sickly young king. Folkingham was granted to Edward Clinton, Earl of Lincoln, but when the 3rd Duke of Norfolk was released and compensated by Mary I (Bloody Mary), it appears that he and Lord Clinton exchanged land, the Duke of Norfolk gaining lands in Devon and Somerset, and Clinton the lands in Lincolnshire. By this time, the castle was deteriorating, and was apparently being used as a quarry by local builders.