Thenford House had seen little attention since Queen Victoria’s day. The garden immediately around the house had, however, been cared for and the two acre walled garden had continued in active use until after the Second World War, although by the 1970s its use was largely given over to the rearing of lambs secure from the foxes for which the Bicester Hunt was famed. Michael and Anne Heseltine purchased the house and its surrounding garden in 1976, whilst adding over 400 acres of agricultural land to the horticultural and agricultural assets of Haymarket Media Group.
The arboretum, now spread out over seventy acres, features a collection of more than 3,000 different trees and shrubs, together with extensive herbaceous borders, water gardens, an alpine trough garden, a sculpture garden, a rose garden and a rill. The medieval fish ponds, their interconnecting canal and the existing lake have been restored and two new ones have been added. An eighteenth century avenue of mature yews has been cleared of self seeded shrubs and saplings, and returned to its former grandeur.