A Heritage Impact Assessment was requested at a proposed development to the rear of Englefield Cottage in Harwell (NGR SU 49126 88861).Englefield Cottage is a grade II listed timber framed building with a thatched roof. It is one of a number of listed buildings in the area, others include Cyprus House, Wellhead, Abbey Timbers and Gable and Tibberton Cottages. These buildings are located in the Harwell Conservation Area. All of these heritage assets are thus designated as significant nationally. There are the possible remains of a hollow way on the site.The proposal site borders and lies adjacent to the Conservation Area and can thus be considered to lie in the buffer zone of that designated asset.The site can clearly be recognised as a potential building plot. The construction of a building adhering to traditional designs is in keeping with the two listed buildings Englefield Cottage and Cyprus House. There is probably a minor impact visually for Tibberton Cottage and Abbey Timbers. This impact would have to be mitigated by landscaping.