The main range comprises the great hall, reached through the entrance porch in the base of the clock tower. The porch floor is laid with Minton tiles (designed by Pugin) and its walls are faced with linenfold panelling. It has a simple panelled ceiling. Doors to R and L lead to spiral stairs which have stained glass panels, and lead up to the clock tower and gallery in the hall. The doorway to the hall is under a Tudor arch and above it, in relief, is foliage with 'WELCOME' in archaic script. The half-lit doors have Perpendicular-style tracery with stained glass, above linenfold panelling. Clock cabinet in 2nd storey room of tower, with clockface under balcony facing Great hall: the clock was ordered from Wagner of Paris in 1855-6 and installed in the tower in 1858; ornate oak case with ornamental bronze work by E. Vittoz.
The great hall is the showpiece of the interior. It has a hammer-beam roof, with lions on the ends of the beams, which stand on wall shafts with foliage and shield corbels. The underside of the roof is composed of a frieze of Welsh family shields below a ceiling of stained glass consisting primarily of foliage in quatrefoils. Suspended from the ceiling, by means of knotted 'ropes' of iron, are 3 large cast iron chandeliers. These are composed of a large orb with pendant, and sprouting tendrils which form into the bodies of cherubs who hold further tendrils in their outstretched arms. Between each cherub is a bird or animal head in a shield on the central orb. A Tudor-style fireplace has a large overmantle with raking hood. The walls have linenfold panelling. There are galleries in each corner of the hall, and a larger one on the W side entered from the clock tower. All have wrought iron balustrading in Gothic style. To the W gallery is a pair of doorways formed of crocketed Tudor arches, flanked by empty statue niches. The upper W windows have stained glass which incorporates Naylor's monogram, heraldic devices, and in the margin lights Naylor's personal rebus (a nail with the letters 'o' and 'r').
From the hall there is the library on the S side, the service wing on the E side and a range of rooms in the N wing, parallel to which is a long corridor, which also gives access to the service wing. The doors to the main rooms have linenfold panelling in moulded surrounds with brattishing. The main rooms also have linenfold panelling around the walls.
From the hall, the first 2 rooms of the N wing have panelled ceilings with gilding and polychrome stencil painting of naturalistic foliage, on painted cornices of foliage trails and billets, decorated by Crace to Pugin’s designs. Each room also has an opulent alabaster fireplace consisting of a Tudor arch below a quatrefoil frieze, above which is a large mirror flanked by compound shafts and with brattishing above. The windows in each room have shutters with linenfold panelling. A third room in the N wing, immediately beyond the previous 2, has a plainer panelled ceiling (above a cornice of vine trails) which has gilded foliage bosses, and panels (some of which are lozenge-shaped) with stencilled foliage more stylised than in the other rooms.
The library has a panelled ceiling painted white (although the original stencil painting of naturalistic foliage is exposed in one small panel) above a cornice of foliage trails. It also has a large fireplace similar to those of the N wing, but in stone, which has a quatrefoil frieze incorporating Naylor's monogram and the heraldic device of dragons rampant.
The corridor of the N wing is laid with Minton tiles and contains the main open-well stair immediately behind the Great Hall. The stairwell is top-lit, having a stained glass octagon containing a variety of devices, including Naylor's monogram. The stair has a wreathed handrail, newels carved with foliage and rosettes, thick balusters, strings carved with foliage and a panelled dado.
The service wing includes an original strong room with cast iron door and safes. Most of the rooms have their original cupboards and there are also some large slate floor slabs.
On the first floor several rooms in the N wing have marble fireplaces. All the main rooms have doorways with embattled surrounds and doors with linenfold panelling, and linenfold panelling beneath the window sills. Within the roof are lead-lined troughs which collect water from the roofs, and which was then stored in a large cistern in the cellar. The cellars also have slate slab floors and ceilings, alcoves and compartments with slate shelves.