The reserve was set up in 1975, to be run by the Basildon Natural History Society. It was formally opened in May 1981. At that time the site was owned by the Basildon Development Corporation, which had acquired it along with a great deal of other land, in the course of planning to develop the South-west Area of the designated New Town. A public enquiry into the Corporation’s proposals in 1975 had the result that significant parts of the proposed development were refused, not least in the Willow Park area and on Dunton Ridge. Discussions had already been going on concerning the possibility of setting up a nature reserve on some of the woodland and plotland on Marks Hill, and this became more feasible once it was clear that much of the adjacent land would be free of development.
Virtually from the outset, the nature reserve at Marks Hill enjoyed Development Corporation support, perceived as an integral part of the planned New Town. Material help was forthcoming in getting some of the area fenced, and the BNHS was entrusted with the management of the reserve, with the support of the Corporation.
When, in 1986, the Corporation was in the process of winding up its operations, the EWT was granted a long lease on the reserve, sub-leasing it to the BNHS. Then in 1989 the actual ownership of the site passed to the Essex Wildlife Trust, when the 460 acre Langdon Nature Reserve was purchased and set up. Since that date, the BNHS has continued to manage the wood, via a formal arrangement with the EWT.