[6] It holds a particular importance due to its ownership by, and role in entertaining, Tudor and Stuart monarchs; Elizabeth I inherited the estate from her father Henry VIII and her successor, James I, personally contributed to its 1622 extension, housing the state rooms and featuring some of the most important surviving plasterwork and fireplaces of the period.

[7] There were at least thirteen extended royal visits – more than to any other house in the county – between 1566 and 1636,[8] and it was at Apethorpe, in August 1614, that King James met his favourite and speculated lover, George Villiers, later to become Duke of Buckingham.

[19] In September 2004 the entire remaining estate was compulsorily purchased by the British Government under section 47 of the Planning (Listed Buildings and Conservation Areas) Act 1990.

Much of the work was carried out by Stamford restoration and conservation builders, E. Bowman & Sons Ltd. From 2007, buyers were sought, in spite of an estimated £6 million still required in renovation (as of 2014, the house was without any plumbing, power or heating).

In December 2014, English Heritage announced that Baron von Pfetten, a French anglophile and keen field sportsman, had bought the property.

Simon Thurley, English Heritage's chief executive, welcomed the purchase:[21] "Since 2000 English Heritage has consistently said that the best solution for Apethorpe is for it to be taken on by a single owner, who wants to continue to restore the house and to live in it; especially one who has experience of restoring historic buildings and is prepared to share its joys with a wide public, as Baron Pfetten will do.

[21] Before the sale English Heritage and Baron Pfetten agreed to rename the house "Apethorpe Palace" due to its royal ownership and use, along with its outstanding historic and architectural significance.

[22] In a video introducing the sale, English Heritage director Simon Thurley described the house as "the Royal Palace of Apethorpe.

This suite of state rooms consisted of the Dining Chamber, the Drawing Chamber, the King Bedchamber, the Prince of Wales Bedchamber (with the three feathers carved on the fireplace) and the Long Gallery (last complete set of original Jacobean State apartments left in England).

[20][34] The discovery of the secret passage, according to Emma Dabiri, provides an "intriguing clue to the nature of the affair" between the King and Duke, who wrote each other love letters and were inseperable, she says.

The restoration and attempts to sell the property were the subject of a fly on the wall documentary first shown on BBC Two in April 2009.