In 1516, Henry VIII granted Grimsthorpe  to William, 10^th Baron Willoughby de Eresby as a wedding present. Lord Willoughby married Maria de Salinas, kinswoman and lady-in-waiting to Catherine of Aragon. A housekeeper’s book from 1560s mentions payments to weeder women for weeding the ‘inner courts’.

On inheriting the property in 1666, Robert Bertie, 3^rd Earl of Lindsey rebuilt the north front of the 16th century house and laid out the gardens. The architect was possibly William Winde or Robert Wright.

His son Robert who succeeded him in 1701, commissioned Stephen Switzer to create a formal garden within a working landscape. The design, similar to one illustrated in Switzer’s Iconographica Rustica (1715), was made up of ten spikes terminating in bastions with a central avenue leading to the Groves. Switzer had worked at Brompton Nurseries for George London and Henry Wise where he would have met the architect John Vanbrugh. Perhaps to celebrate his dukedom, the 4th Earl asked Sir John Vanbrugh to redesign the house.

The Walled Gardens first appear on Grundy’s estate map of 1753.

In 1771, ‘Capability’ Brown was commissioned by 3rd Duke of Ancaster and Kesteven to update the park. The Dukedom became extinct in 1809 with the baronetcy passing to Lady Priscilla Bertie who became 20th Baroness Willoughby de Eresby.

The Castle was remodelled in 1810s with further alterations in the early 20th century by Detmar Blow.

After the property was requisitioned by the army during the Second World War, further restoration work was carried out by the 26th Baron.

It was at Grimsthorpe Castle that in 1964, Nancy Astor died surrounded by her family. Her daughter had married Gilbert James Heathcote-Drummond-Willoughby in 1933, thus becoming Countess Ancaster.

In 1978, a charitable trust was created to maintain the Castle and the surrounding estate.

The current owner of Grimsthorpe is Jane Heathcote-Drummond-Willoughby, 28th Baroness Willoughby de Eresby, granddaughter of Nancy Astor. Lady Willoughby also inherited Drummond Castle from her father. Her brother, heir apparent of the Earldom of Ancaster, was lost at sea in 1963 and the Earldom became extinct.