Bonhill Cottage was assessed for designation as a Listed Building in 2019. The decision was taken not to list the building.

From the assessment report: "Bonhill Cottage, 1864, was built as an estate workers’ cottage associated with Winfield House (listed Grade II). The quality of the exterior materials and craftsmanship is worthy of note, in particular the galetted joints of the stonework and the use of smooth-faced gault brick detailing (now largely painted). In other aspects the building is curious: the tall proportions, old-fashioned styling, the almost identical symmetrical front and rear
elevations, and a floor plan which requires each of the main rooms to have two doors for convenient
circulation. This unusual but slightly awkward architecture suggests that the design was perhaps the work of a builder, not a professional architect. Not unsurprisingly for an estate cottage, greater effort has gone into the exterior styling of the building than the interior fit-out. What remains of the original fittings, most obviously the doors and some skirting, indicates that the interior was always modest.

The building has undergone a number of alterations, including two extensions. That to the north has a lesser impact than that to the east, which is on the front of the building and has required the loss of one of the window openings and the repositioning of the front door. Internally there has been the loss of fireplaces and some joinery. There will almost certainly have been losses of other fittings too, but these can only be speculated.

Historically the building is connected with Winfield House which, although listed, does not have particular claim to historic interest above many other houses of its type. The unlisted Winfield Cottage, which is stylistically similar to Bonhill Cottage and was also part of the Winfield estate, has a visual relationship with Winfield House because of its proximity, but this is not the case for Bonhill Cottage which is located a short distance away.

Bonhill Cottage has local interest for its use of materials; distinctive, if slightly eccentric composition and plan; and association with nearby Winfield House. It is however also a relatively late, modest building which has undergone notable alteration and which does not have strong group value with the house with which it is associated."

Historic England, 2019, Historic England Advice Report: Case Name Bonhill Cottage, Crouch (Unpublished document). SKE52334.