A large 3-storey house with attic, mainly Tudor-Gothic style of many periods, and roughly square in plan with ranges grouped around a central 5-stage tower. Of rubble stone with larger quoins, slate roof behind coped gables, and numerous tall stone stacks. Windows are generally consistent in having ovolo-moulded mullions and transoms in ground and 1st floor, and plain chamfers to the 2nd floor. The various components of the house are described in approximate date order. The 5-bay entrance front faces NW. It is near symmetrical with projecting gabled end bays, and 3-storey central porch slightly lower than the main house, which was added in 1894. The 1st and 2nd bays were added in the late C17 and have been called the servants' hall. Bays 3-5 are the 1620 hall house with added porch.
The porch has a Tudor arch with continuous chamfer, and C20 boarded doors. The 1st-floor oriel, incorporating a cross window, is on freestone corbelling with heraldic shield bearing a Mostyn lion. The oriel and outer corbels support the 2nd-floor 3-light window. Offset slightly L above the porch the main house has a gabled dormer with 2-light mullioned window. The narrow bay on the R of the porch has 3-light windows under dripmoulds, and relieving arches to ground and 1st floors. In the projecting, gabled R end bay are 3-light windows, and ground and 1st-floor relieving arches. The gable is pedimented with a thin cornice, where there is a blocked attic window under a drip mould. In its L-hand return wall this bay has a corbelled stack with tall shaft, behind which, in the angle with bay 4, is a lead rainwater head, with downpipe, inscribed 'MW 1765' in relief.
In the R gable end, facing SW, the ground level is lower. The basement storey has a entrance in a segmental-pointed arch with studded door. Ground and 1st floors have 4-light windows with dripstone. In the 1st floor the dripstone is carried over a tablet with '1620 R K W' (Robert and Katherine Wynne) in relief. The 2nd floor has two 2-light windows under dripstones, and the attic a similar single window. All windows in this elevation have relieving arches. On the R side, in the angle with the 1894 drawing room, a lead rainwater head is inscribed 'MW 1765'. The rear, above the drawing room, has a mullioned 1st-floor window.
The embattled rear tower is directly behind the 1620 hall and rises 3 stages from the main stair turret at 2nd-floor level. It has its own stair turret in the SW wall, against which is the lateral hall stack. The turret has superimposed 1-light and 2-light windows. To its R the tower has a blocked window and 3 further superimposed 2-light mullioned windows with dripstones, and on the R side a rainwater head with 'RW 1752' in relief.
Returning to the NW entrance front, the 2 L-hand bays belong to the late C17 servants' hall, of 3 storeys with end stone stacks. In the wider gabled 1st bay are 2 cross windows to the ground floor, 2-light 1st-floor windows and smaller 2-light 2nd-floor windows. In bay 2 immediately L of the porch are string courses at the level of the windows in bay 4, but altered C19 windows. These are paired cross windows in the ground floor, paired 2-light 1st-floor windows under a narrower original relieving arch, and small 2-light 2nd floor window.
The NE front of the servants hall is approximately 3 bays and asymmetrical. In the R-hand and the narrower L-hand bay are 3-light transomed ground-floor windows, smaller 3-light transomed 1st-floor windows, then a string course and 2-light 2nd-floor windows. The elevation is dominated by its advanced central bay, under a crow-stepped gable with apex ball finial, added in 1884 to house a stair. It has a large double-transomed 4-light stair window with patterned and coloured glass, and a hood mould extending over the jambs, the top of which bear the date in raised numerals. Above the main window is a 3-light plain chamfered window, and below the stairs are paired 2-light windows, also with plain chamfer. Set back on its L side is a narrow hipped turret.
Projecting at the L end of the NE elevation is the 1730 NE service wing. This is a gabled 3-storey wing with end stack. In the gable end its ground floor and 2nd floor have 2 wooden cross windows. Original 1st-floor windows are blocked but their segmental relieving arches remain visible. Above them in the centre is a tablet with 'RW 1730' in relief. In its R side wall, facing the servants hall, is a lean-to chimney projection, a 2-light plain-chamfered 1st-floor window with drip mould and relieving arch, and blocked 2nd-floor window.
Set back on the L (SE) side of the NE service wing are additions of the last decade of the C19, probably 1894, and shown on the 1900 Ordnance Survey. Openings have stone lintels, windows are wood-framed casements with leaded glazing, and between 1st and 2nd floors is a thick roll mould. A slightly lower canted projection against the 1730 wing has a steep swept pyramidal roof with lead finial. It has 1-light windows to 1st and 2nd floors. An adjoining gabled projection facing SW has its entrance on the NE side up slate steps with stone parapet, with recessed boarded door under a cambered head. This entrance is integral with an external stack. Its gable end has 2 ground-floor windows, a single 2-light 1st-floor window and 3-light 2nd-floor window. The L side wall has two 2-light windows in the ground floor, cross windows to the 1st and 2nd floors. Set back to the L, between the gabled bay and 1905 SE service wing, is a 2-window section of the side wall of the 1730 wing. It has 2-light ground-floor windows, cross windows in the 1st floor, 3-light with transom and cross window in the 2nd floor.
Additions of 1894 and 1905 dominate the SW elevation. This elevation is composed of the original 1620 house on the L, a gabled bay set forward in the centre, with another set back on the R, both of 1894, then the SE service wing of 1905 at R angles set further back to the R end. Immediately R of the 1620 wing is a projecting 1-storey former drawing room with crow-stepped gable. It has a large bay window under a coped gable with apex finial and ball finials on the eaves. It has a 5-light double-transomed window and 2-light returns, with coloured leaded glazing above the upper transom. In the gable is a tablet with '1894 HLlM PGM' in relief. The L side wall has a single window. In the R side wall of the drawing room are replacement French doors in an original opening under a mullioned overlight.
Set back further R is another gabled bay, of 3½ storeys and incorporating the dining room, also of 1894. It has a pair of 3-light transomed windows in the ground floor, 4-light windows to 1st and 2nd floors, with drip moulds, and small narrow attic window. A narrow outshut is set back on its R side, and set further back is the SE service wing, hipped to the L. In its angle with the lean-to on the L is a quarter-round corbelled 2-light oriel (a similar window is at Plas Mawr). Otherwise the SE wing has 3-light and 2-light ground-floor windows. The 1st floor has a pair of 2-light windows, its drip mould carried over a central tablet with '1905 HLlM PGM' in relief. The 2nd floor has a pair of 3-light windows under a single drip mould, and a gable. In its R-hand (SE) gable end, facing the rear service yard, is a corbelled 1st-floor stack. It has a hipped lean-to at basement level with boarded door in its R-hand return, and flanked by casement windows. Above is a casement window on the R side of the 1st floor, and 2 single 2nd-floor windows in dressed surrounds with drip moulds. The rear wall facing the yard has a 1-storey hipped lean-to with a boarded door and fixed leaded window in the side wall. In the 2nd floor is a 2-light casement. The angle between SE and NE service wings has a full-height projection under a pyramidal roof, with 1-light and 2-light windows.