Chiswick House Conservatory, Hounslow, London

Summary

Conservatory, built as a hothouse for fruit species in 1814, used as a show house for flowers by about 1828. Altered with new glazing and a modernised heating system in 1855. The glazed superstructure was replaced in 1932 to 1933 by Messenger and Co, and again in 2008 to 2010 closely matching the 1930s glazing pattern but retaining the patent clear span post-tensioned steel rafter system and rods and gears providing the roof ventilation system.

Description

MATERIALS: a timber glazed lean-to structure with cast-iron supports and steel bracing, and brick rear service range with a slate roof covering.

PLAN: one long glazed conservatory lean-to range with a semi-circular projection at the centre and pavilions at the ends separated by a central brick wall from a lean-to service range at the rear. The service range contains the original furnaces and cisterns that would have been used to heat and irrigate the hothouse.

EXTERIOR: the conservatory is set on a south-east-facing terrace approached by stone steps and looking out onto an Italian Garden. It is orientated north-east to south-west. The building has a symmetrical glazed timber superstructure resting on a rendered brick dwarf wall, which is built as a lean-to against a substantial central brick wall separating it from a rear lean-to service range. The dwarf wall has a Portland stone plinth, cill and upstand over it. At the centre is a semi-circular projection with a facetted glazed roof surmounted by a glazed drum, dome and small lead cupola with a weathervane. The conservatory is entered at the south-east by a pair of central glazed doors and lit by a continuous band of nine-paned top-hung windows beneath a clerestory of small square leaded lights. Adjoining the central semi-circular projection is a lean-to with nine-paned windows, a clerestory of small square leaded lights, and a glazed roof. Set lower, and flanking it, are two long wings, each of 28 bays with a continuous band of three-light top-hung windows, small square clerestory lights and a glazed roof. Each wing has a projecting gabled porch at the centre of the south-east side with glazed double doors and glazed roofs. There are pavilions at each end, again set lower, which were formerly pineries with gabled porches. The rear elevation of the building is formed by the lean-to brick service range under a slate roof. This range has a central pedimented entrance containing a glazed double doorway with transom lights. It is rendered and applied with detailing to imitate ashlar masonry. The first five bays flanking this entrance on each side were originally open to allow access for wagons and carts. However, they have been infilled in weatherboarding with ribbon glazing and boarded doors, whilst three of the bays at the north-east are set back to form a covered walkway supported on modern columns. The remaining seven bays to each side of the rear range have three-light casement and fixed windows, some of which have further subsidiary bars, and a doorway containing a panelled door at each end. The top of the central brick wall has a lead flashing, concrete coping and cast-iron classical urns situated next to the chimneys. The rear service range is covered by a slate roof.

INTERIOR: the glazed timber superstructure of the conservatory was replaced in 1932 to 1933 by Messenger and Co, and again in 2008 to 2010 closely matching the 1930s glazing pattern. However, the Messenger clear span roofing system, consisting of cast-iron mullions anchored to the masonry dwarf wall with cast-iron brackets holding the steel tension bars that allow the rafters to span across the conservatory, was retained and remains in place. The Messenger system of rods and gears to open the roof ventilators in banks, in order to reduce the time spent on opening and closing the ventilators, also remains in place. Many of these features are stamped with ‘MESSENGER & CO LTD LOUGHBOROUGH’. These features, together with the overall form, design, and glazing pattern of the conservatory are all of a high degree of significance, although the current glass and fabric of the timberwork itself is of lesser interest given that it has essentially seen replacement as recently as 2008 to 2010 (with minor repairs in 2020). The main entrance to the conservatory leads into the central semi-circular projection, which has a flagstone and York stone paved floor in which are set some decorative cast-iron underfloor heating grates. Beneath the dome is a circular geometric pebble mosaic situated where the original basin containing exotic plants was positioned. There are ten cast-iron piers with moulded bases and capitals supporting the glazed drum and dome above. An arch leads through into a barrel-vaulted entrance hall at the centre of the rear range, which has a ceiling rose and an elaborate bed moulding decorated with anthemia, bead-and-reel and foliated decoration. The centre of the conservatory is flanked by long wings, which have York stone paved flooring and a flower bed containing the historic camellias next to the back wall which is rendered on this side. A two-tier paved platform, supported by moulded stone columns, chamfered stone piers and stone blocks, runs the length of the front wall. This would originally have been used to display pot plants. Beneath the lower platform are the large heating pipes* added in 1990, whilst elsewhere there is a modern lighting system* and associated electrical fixtures*; all of these features are not of special interest. The platforms continue into and around the walls of the former pinery compartment at the south-west end, which also has a York stone paved floor, trenches for the heating pipework (and possibly water collection) and decorative heating grates. The former pinery pavilion at the north-east has had the platforms removed, forming a single paved open space. Adjacent to the internal entrances to the pavilions are panelled historic doors with brass door furniture that lead into the rear range.

The rear service range is currently (2022) used for volunteer activities and storage purposes at the south-west but has been converted to offices at the north-east end. This range has lean-to timber roof trusses and three of an original six brick and stone furnaces (or stoves) that heated the fruit house remaining in place. The furnaces have brick arches for openings (now bricked up) about 1.5m wide and were fed by coal to reach very high temperatures in order to induce a flow of hot air along the conservatory hypocausts. These ran through the partition wall, across the planting beds, and under the windows before returning to vertical flues that emerged through the chimneys. Positioned above the furnaces are large stone water storage cisterns originally used to irrigate the conservatory plants. These cisterns are 3.9m long, 1.9m wide and 0.8m deep. They may once have been fed from gutters collecting rainwater from the roof of the range. This service range would originally have been used for drying and storing produce from the kitchen garden as well as preparing crops for planting. There are a few remaining circular wooden poles fixed between the roof trusses that appear to have been designed to store kitchen garden produce for drying and made detachable for cleaning. At the west end of the service range is a large brick vaulted water tank that was inserted in about 1855, cutting through one of the principal truss tie beams. It may originally have been used to feed the fountain in the Italian Garden. Next to this tank is a brick pit for the boiler, originally created in 1855, but now containing a modern boiler* installation which is not of special interest. The service range has a brick floor, partly laid in a herringbone pattern. The western part of this range has a stone tank next to one of the cisterns, a later inserted brick fireplace with a hob grate, and some weatherboarded partitions. The eastern part of the range has a staff room with modern kitchen units* and a disabled ramp*, toilets with modern sanitary ware*, and offices with two brick fireplaces, some inserted modern false floors* (above the earlier brick flooring), false ceilings* and a number of modern fixtures, fittings and services* which are not of special interest.

EXCLUSIONS
* Pursuant to s1 (5A) of the Planning (Listed Buildings and Conservation Areas) Act 1990 (‘the Act’) it is declared that these aforementioned structures and/or features are not of special architectural or historic interest. However, any works to these structures and/or features which have the potential to affect the character of the listed building as a building of special architectural or historic interest may still require Listed Building Consent (LBC) and this is a matter for the Local Planning Authority (LPA) to determine.

History

The property at Chiswick was occupied by a Jacobean house (demolished 1788) and associated formal gardens from the mid-C17. In about 1727 to 1729, a Palladian villa (the current house, Grade I-listed) was added alongside a scheme of formal gardens with the intention of re-creating the architecture and gardens of ancient Rome under Richard Boyle, the third earl of Burlington. Several further phases of extensive gardens were added during the C18, including the first ‘natural’ or landscaped gardens under Burlington and William Kent from 1733.

William Cavendish, Sixth Duke of Devonshire, inherited the Chiswick estate in 1811 and acquired the adjacent property, then known as Moreton Hall (built in 1682 to 1864 for Sir Stephen Fox to the designs of Hugh May) the following year. The house was demolished, but its sequence of walled gardens were added to the Duke’s estate and both gardens were thereby combined into a single site (Grade I-registered). The walled enclosures to its north were used as kitchen gardens while a new Italian Garden was laid out in the southern section (originally Fox’s pleasure garden), which was one of the earliest instances of the revival of formal gardens after the long reign of landscape gardens in England (Woudstra 2010, 111). It was one of the earliest formal gardens to come under the name ‘Italian Garden’, preceded only by one at Mount Edgcumbe (Ibid, 111). Such gardens were typically characterised by symmetry, formality and hardscaping with terraces supported by parapet walls on the coping of which vases might be placed, as well as geometric beds often planted with evergreens. The Italian Garden was laid out to the design of Lewis Kennedy in 1814. It included a 92m long conservatory designed by Samuel Ware, architect for the Burlington Arcade (Grade II-listed), and built at a cost of £15,000. The building was positioned to separate a kitchen garden and melon ground to the north from a semi-circular formal garden at the south. The conservatory stood on a raised terrace, in order to visually extend its height and act as a base, with a flight of steps at the centre and to each end leading to the south where there was a central gravel path flanked by hedges, with narrower paths behind them, in parallel, as well as a number of parterres filled with classical patterns. Kennedy declared his completed design as ‘unique in this style of gardening for beauty, grandeur and magnificence’ (Ibid 114). When viewed from the terrace in summer, with all the plants filled out, it was subsequently said that there was ‘nothing of the kind in the neighbourhood of London at all equal to it’ (Edward Kemp, 1851, cited by Woudstra 2010, 117).

The conservatory was a lean-to south-facing fruit house except for a glazed semi-circular central projection with a gilded dome containing stained glass (a detailed history of the building is set out in McLaren 2005). The building is thought to be the earliest large glasshouse built and was a forerunner of Decimus Burton’s hothouse at Kew, and Sir Joseph Paxton’s at Chatsworth and Crystal Palace (Burns 2011). It has been suggested that the use of the central dome was pioneering, marking a transition from kitchen garden glasshouse to elegant conservatory, and that the building was notable for pre-dating the invention of curvilinear wrought-iron glazing bars introduced in 1830 (LDA Design, Gazetteer, 46). Beneath the dome there was a fountain and basin containing exotic aquatic plants. The building was originally fitted with sliding sashes glazed with small panes of crown glass. This superstructure was supported on a purlin and iron posts at mid-point resting on stone plinths. Around the perimeter of the central dome were doors that could be opened to provide ventilation. The conservatory contained peach trees, grapevines and pineapples. In terms of layout, it comprised nine compartments: two pineries at each end, the central domed compartment, and three compartments in each wing. The divisions corresponded to the heating furnaces and flues and enabled different climates to be maintained in each compartment, allowing produce to ripen at successive times throughout the growing season (McLaren 2005, 15). Set behind the glasshouse at the north was the lean-to potting and storage range, probably including a bothy for the gardeners. The bottom of the central division wall was pierced with arches to take the roots of the peach trees through to the back sheds and into a long soil-filled narrow trench running at the foot of the wall (Ibid, 17). This allowed the roots to be contained in order to restrict growth, encouraging the production of fruit by placing the plant under pressure to propagate seeds (the fruit) for survival. The external front wall and front and back walls of the pineries, as well as the main south wall of the conservatory, were also pierced by arches to allow vine roots to be grown in external beds. All of the arches appear to remain in place, although partly infilled, today (2022). The vines were originally trained up the roof rafters internally.

The original heating system comprised a network of hypocausts which were fed with warm air created by six coal-fired furnaces (three of which survive) located in the back range positioned beneath large water storage cisterns. There were two further furnaces heating the pineries, but these have been removed. The hypocaust flues ran around the planting beds and beneath the central basin under the dome, possibly also warming the water to increase the humidity to suit the exotic plants being grown there. This heating system consumed over 100 tons of coal per year at one point. Partial excavation has shown that hypocaust flues survive below-ground within the current building and are constructed of four courses of bricks set on edge with a tiled floor and capping. The rear service range contains large irrigation cisterns for the conservatory plants and the furnaces noted above and would have been used for drying and storing produce from the kitchen garden as well as potting and preparing crops for planting. The first five bays on each side were originally open to allow access for wagons and carts. Within the range are drying poles; detachable circular poles positioned horizontally between the trusses. At the south-west end of the range is also a brick vaulted water tank; its purpose is currently unknown but it may have fed the fountain in the Italian Garden.

Camellias were planted in the conservatory (originally in pots) in 1828, which subsequently saw a change in use from a fruit house to a show house. They were imported by Chandler and Buckingham of Vauxhall at considerable cost from China and are one of the oldest collections under glass in Europe. Many of the original 40 varieties still survive (there were some 33 varieties in 2022), making the collection probably the largest in Britain and possibly outside of China and Japan (Burns 2021). It contains specimens of four of the earliest camellia varieties introduced into Europe: Camellia japonica (about 1739), C japonica ‘Rubra Plena’ (1794) C japonica ‘Variegata’ (1792) and C japonica ‘Alba Plena’ (1792) (Ibid). There is also the Middlemist’s Red, one of only two of this variety known to exist in the world; the other being in Waitangi, New Zealand. The variety was brought to Britain from China in 1804 by John Middlemist, a nurseryman from Shepherds Bush.

In about 1855, a series of changes were made to the conservatory. The existing hypocaust heating system was replaced with a gravity-piped hot water system fed by boilers located in pits at each end of the back range; the hypocaust trenches appear to have been adapted to accommodate the cast-iron pipes. In conjunction with this, or before, most of the partitions of the compartments were removed. The small panel glazing was replaced with larger panes, probably using Hartley’s Patent Rolled Plate; glass produced with finely combed grooves for diffusing the sun’s rays and preventing scorching to the plants (McLaren 2005, 57 and 59). Two platforms formed of stone flags to display pot plants were built replacing the vinery planting bed, at the front of the conservatory. The planting at this time is recorded as including: pelargoniums and azaleas to the platforms when in flower with a mixed collection the rest of the year; camellias and rhododendrons to the rear bed; acacias, passion-flowers, tacsonia and climbing plants on pillars along the walkways; a wisteria and a Rosa banksiae trained inside the dome, and camellias, rhododendrons, and a cluster of rarer plants in the beds below. There may have been some further works to the conservatory in 1895 (LDA Design 2004).

The Chiswick House estate was let to a series of aristocratic tenants after 1862 before becoming a mental health institution or asylum from 1892 until 1929. The Italian Garden was re-arranged by the gardener Michael May in 1880 and the beds planted with herbaceous plants and annuals. In 1929, the estate was sold to Middlesex County Council and subsequently leased to Brentford and Chiswick Urban District Council for use as a public park. In 1932 to 1933, the glazed conservatory superstructure was replaced with a patent clear span post-tensioned steel and timber rafter system by Messenger and Company of Loughborough, with hinged ventilators in place of the sliding sashes and cast-iron mullions (Ibid 65). This was one of the last glasshouses built by the company, which had ceased this work by 1940, and was constructed at a cost of £2188 (Ibid 68). The overall form generally matched the previous superstructure but the detailing appears to have been simplified and the central semi-circular projection was rebuilt with a dome raised on a faceted drum. In 1941, the rear service range and north entrance porch suffered some damage during Second World War bombing and repairs were subsequently carried out. The Beatles filmed early music videos of their singles ‘Paperback Writer’ and ‘Rain’ under the conservatory dome and gardens in May 1966. The conservatory underwent some like-for-like repairs in 1983 and there were some repairs to the dome in about 1990. The camellia collection was described as approaching ‘terminal decline’ in 1994 but was rehabilitated by volunteers from the International Camellia Society (McLaren 2005, 30). The glazed superstructure of the conservatory was replaced in 2008 to 2010, closely matching the 1930s glazing pattern and retaining the earlier iron and steelwork. The Italian Garden was also partly restored to the 1880 scheme at this time. Small-scale repairs were carried out to the conservatory in about 2020.

Reasons for Listing

Chiswick House Conservatory built to a design by Samuel Ware in 1814 but altered in 1932 to 1933 and 2008 to 2010, is listed at Grade I for the following principal reasons:

Architectural interest:

* as an early C19 fruit house which retains the original rear service range and a number of important early internal features, despite later replacement of the glazed timber superstructure;
* for the surviving early C19 coal-fired furnaces and much of the hypocaust from the original heating system, as well as the large cisterns from the original water irrigation system, and the drying poles, all of which have been identified as unusual and important features that may now be the only such examples surviving, as well as the 1855 vaulted water tank and boiler pit;
* for the architectural interest of the rear service range with its pedimented entrance and vaulted hall, as well as the conservatory interior with its tiered platform of 1855 and surviving ironwork;
* for the relatively rare surviving features of the 1930s Messenger roofing system to be built on this scale, including the cast-iron mullions anchored to the masonry dwarf wall with cast-iron brackets holding the steel tension bars that allow the rafters to span across the conservatory, as well as the rods and gears to open the roof ventilators in banks.

Historic interest

* originally built in 1814 to the design of Samuel Ware, architect for the Burlington Arcade (Grade II-listed), as, what is thought to be, the earliest large glasshouse built; a forerunner of Decimus Burton’s hothouse at Kew, and Sir Joseph Paxton’s at Chatsworth and Crystal Palace, with the notable use of a central dome, and which retains the original rear service range and many internal features despite later replacement of the glazed timber superstructure to a similar design;
* as part of the Italian Garden at Chiswick House; one of the earliest formal gardens to come under that name, preceded only by one at Mount Edgcumbe, and, more generally, one of the earliest instances of the revival of formal gardens after the long reign of landscape gardens in England;
* as an early free-standing fruit house with a heating and irrigation system that was converted into an important showhouse for flowers from around 1828, following the importation of camellias from China, which is now one of the oldest collections under glass in Europe, as well as probably the largest such collection in Britain, and possibly outside China and Japan, within the Grade I-registered garden;
* the 1930s replacement to the timber superstructure was probably the last large glasshouse built by Messenger and Company of which the glazing pattern and roofing system have been retained.

Group value

* for the strong group value with the Grade I-listed Chiswick House, the Grade I-registered Park and Garden and numerous designated structures in the gardens.

External Links

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