During the 17th and especially the 18th century the pressure for enclosure was not just for conversion to pasture. Increasingly it was seen as a way of improving mixed farming too. To stop the minor landowners and commoners, who had the most to lose, from blocking the process, a new system of enclosure by private Act of Parliament was introduced. It did provide some safeguard of the interests of the lesser parties and certainly improved the efficiency of the system. The earliest parliamentary enclosure in the forest was at Wakerley and Wittering in 1748/9.
The remaining 54 townships in the forest which still had working open fields were finally enclosed during this period. Some already had large areas of ancient enclosure, as for example at Harringworth and Brigstock where the deer parks accounted for just over half the area of each township. But many townships were still dominated by the open field system. Some had a mix of resources. At Easton on the Hill and Collyweston in addition to the open fields there were significant areas of meadow, wood and, unusual within the Forest, large areas of heath. But in many other townships, such as Ashley, Sutton Bassett, Cotterstock and Nassington the land use was overwhelmingly arable open field.
On this map of Braybrooke of 1767 the new rectlinear fields and straight roads created by parliamentary enclosure have been superimposed over the open field landscape they were replacing (reproduced by permission of Northamptonshire Record Office)
The landscapes created under the parliamentary system tend to be far more regular and rectilinear in plan form than anciently enclosed townships. The latter had generally seen hedgerows added along exiting roadsides and furlong boundaries. Parliamentary enclosure was planned by surveyors who typically laid out new straight road of standard widths and allotments to all of the landholders with straight boundaries. Then when those landowners subdivided their farms they laid out rectilinear fields too. So today while anciently enclosed townships tend to preserve the basic plan form, especially the road pattern, of the medieval landscape, the parliamentary enclosures represent an almost wholly new plan. This is most clearly seen at Collyweston and Easton on the Hill, where the very flat limestone plateau allowed fields to be laid out in a very regular geometric pattern. Here, unusually, because of the presence of extensive areas of limestone near the surface, many of the field boundaries are stone walls rather than hawthorn hedges.
But it was not just the open field systems that were transformed by enclosure. The parliamentary Acts saw the complete removal of the small tracts of heathland in the north of the forest, especially in Collyweston, Easton and Wittering, which is now either arable land or has been engulfed by Wittering airfield. Enclosure also caused the final phase of destruction of the woodland itself, which had always given the forest its unique character. Once the forest had been enclosed and the common rights extinguished and the land allocated to individual owners, it was very vulnerable to clearance for agriculture. The deer parks and the management for deer had long since gone. So too had the ironsmiths, whose demand for charcoal fuel had been another factor encouraging careful management of the woodland. With the removal of the common rights the last major restriction was gone. As a result, of the 38 square miles of woodland existing at the beginning of the 19th century only 17 square miles in small dispersed pockets remained by the 1880s. On close inspection even apparent survivals can prove deceptive, as at with Southwick Woods which the 1880s mapping shows had been cleared, only to be replanted shortly afterwards. Even where land has remained under woodland the irregular layout of the coppices has been replaced by the rectilinear pattern of more recent ridings.
Today the largest surviving tracts of wood are Geddington Chase, Farming Woods, Westhay and Wakerley Great Wood. But these woods are fragmentary and scattered compared to the large areas of woodland covering several thousands of acres that survived to the 19th century. Morehay in the Cliffe bailiwick alone was over 3000 acres at the beginning of the 19th century. Today it has all but gone. Yet even that which remained in the early 19th century was but a shadow of the great tracts of woodland that still survived in 1300, at the height of the medieval economic boom.