Peckover House Orange Trees

Peckover House is a National Trust property in the north Cambridgeshire town of Wisbech. It is an elegant Georgian brick building situated on the north bank of the River Nene. At the back of the house is a beautiful 0.8 ha (2 acre) Victorian walled garden with interesting and rare trees, delightful summer houses, roses, herbaceous borders, fernery, croquet lawn and 17th-century thatched barn.
It also has a Victorian greenhouse with three sweet orange trees, often said to be 300 years old.
However, there is only one known historical reference to the trees - in fact only to a single tree. In an 1898 book by Frederic John Gardiner, entitled History of Wisbech and neighbourhood, during the last fifty years, it is said that "in the orange house is a tree bearing sweet oranges, purchased at the famous sale in Hagbeach Hall, and at least 200 years old."
Hagbeach Hall, dating from the 1500's and demolished in 1806, was a property in the nearby village of Emneth. It was desribed as 'a commodious and picturesque building with fine grounds around it.' I have been unable to find any further references to orange trees or 'the famous sale' in Hagbeach Hall.