Northfield House sits on a terrace, above the gardens. The house is built in the Scottish tower house vernacular, is two storeys high, irregularly masses, with red sandstone gabled dormers. The gables are curved and resemble an inverted form of Dutch gable. The owner's monogram, WCW embellished with cornucopia and a star, appears in a panel over the front door. Above in Portuguese tiles is a depiction of the Madonna della Catena. The Gardener's Cottage is a square, single-storey building, with a pyramidal roof and tall central chimney. The two timber-framed Greenhouses, sited to the west of the gardener's cottage, have wooden staging. They are contemporary with the house and garden. The Entrance Gates are oak, with a slightly curved top with continuous vertical and horizontal bars forming a square lattice. 'Northfield' is carved into the top of the gate. The gates are replicas of those originally designed for the house.
The house is situated in the western side of the site, with a rockery terrace on three sides.
Situated to the west of the drive, the Herbarium is an informal woodland garden planted with Rhododendrons and Azaleas. The area is divided by narrow, winding, stone paths between woodland plants. A circular grass lawn in the centre of this area once contained formal rose beds. These may have been inserted after Crum Watson's time. There is also an area of lawn and herbaceous borders.
The North Garden compartment contains a fruit and vegetable garden with a central gravel path. This area contains fruit cages and vegetable plots enclosed by box hedging. A large box-edged area on the north side has been grassed over and made into a 'herbe garden', an American concept of formal patterns cut into the grass by using different mowing regimes.
South of the house, the South Garden contains an orchard and four compartments aligned north to south. The compartments are divided by yew hedges (Taxus baccata), with borders of trellised roses and one border of Rosa rugosa. The lower, southernmost compartment is planted with Rhododendron hybrids and terminates in the small formal orchard, quartered by mown paths, with a central tree in a roundel of mown grass. The grass sward in the orchard is managed by as a wild flower meadow and includes common spotted-orchid (Dactylorhiza fuchsia) and snake's head fritillary (Fritillaria meleagris).
The central section is aligned on the east front of the house, and has a circular yew roundel set directly below the terrace leading into a yew allèe. A bank set with a rockery, and a set of central steps, leads out onto a stone path, leading to the roundel. The roundel contains a circular formal garden of box-edged beds laid out in the pattern of a stylised flower, planted with roses and grey foliage plants. Stone paths divide the box beds. The lawn slopes downhill, and is terminated by two sentinel yews at the eastern end.
On their east side, these compartments are joined together by a gravel path which runs north to south. East of the path the central compartment has a small, sunken, rectangular stone-lined pond set with a small stone fountain. The path is lined by pleached lime trees (Tilia x europaea) which continue around the edge of the pond area forming an apse. On either side of the pond, below each of the compartments, is a small copse planted with beech (Fagus syvatica), larch (Larix decidua), and birch (Betula pendula).
The northern side boundary contains mature oak (Quercus robur) and sycamore (Acer pseudoplatanus). To the south there is a small bank with a retaining wall. The banks are planted with mature beech.