The engineering genius of Britain’s great Victorian glasshouses — and how many are in a battle to avoid ‘The Spiral of Doom’

Whimsical and ethereal, as well as feats of engineering, Victorian glasshouses are a reminder of pioneering progress and deserve sensitive restoration, says Lucy Denton.

‘At the spiral of doom’, says Trevor Marrs, head of restoration at Shepley Engineers of Whitehaven in Cumbria, on the right time to repair Victorian conservatories and glasshouses. ‘Once failures start showing up — cracks in cast iron or bubbles in paintwork — they accelerate the longer you leave them.’

Refurbishment of delicate structures such as these is not a simple task and depends on their age and condition, heritage status, original materials used, whether temperate or tropical, architect designed or churned out en masse by specialist firms in the 19th century and, of course, budget. Conservatory development yielded smart inventions, from ridge-and-furrow roofs to advanced heating systems and even ‘beaver-tail glass panes with rounded ends, which were designed to shed rainwater more effectively by directing it down the middle of the pane,’ points out a spokesperson from Historic England’s technical conservation team. Seeking out expert know-how is a must.

Until the 1851 Great Exhibition held in Joseph Paxton’s monumental Crystal Palace, hothouses of all kinds were rarities, out of financial reach of most and usually commissioned by estate owners. But the innovations of the Industrial Revolution spawned technologies seized on by manufacturers who turned out mass-produced greenhouses, opening them up to a wider market that extended to the limits of the Empire.

The 1840s conservatory at Harlaxton Manor, Lincolnshire, had five sections for varying temperatures © Paul Highnam/Country Life

Richard Turner of Dublin, an iron-founder with flair for fashioning superlative glass creations, produced not only the Curvilinear Range at the Botanic Garden in his home city, but the colossal Temperate House at Kew Gardens in London. Assembled in 1863 to drawings produced by Decimus Burton, it was an unparalleled engineering achievement — ‘but he doesn’t get quite enough press,’ says Dr Victoria Perry, practice director at architects Donald Insall Associates, ‘even though he did a lot of the design’.

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Completed in two phases in the 1860s and 1890s, the Temperate House was revamped in the 1970s, leaving behind a patchwork of old and newer fabric and surface treatments, which posed a challenge for the most recent overhaul overseen by the Insall design team in 2013–18.

Sir Donald Insall at Kew Gardens. ©Richard Cannon for Country Life

‘Moisture was the main problem,’ says Richard Barley, director of gardens at Kew. ‘Water ingress had caused corrosion of the metalwork, although there is also a lot of wood in the window structures and roof mouldings.’ The £41 million revamp of the Temperate House, the largest surviving Victorian glasshouse in the world, was a daunting undertaking: if laid out end-to-end, the scaffolding would have orbited the M25. Some 15,000 panes of glass were replaced, 220 urns were refurbished and 3,000 plants, including some that are now extinct in the wild, were reinstated.

‘These are magnificent structures,’ adds Mr Barley, ‘and we shouldn’t let them fall into disrepair. Some of the Victorian engineering is as good or better than what we might do today. Take advice from people with experience, but also take advantage of modern environmental controls, which can be retrofitted.’

From the majestic to the domestic, ornamental triumphs can be found on every scale. Applications have been made to demolish the splendid 1880s conservatory by James Boyd at No 21, Aytoun Road, Glasgow, on the grounds of cost of maintenance, but it need not be so. The similarly sized Halliday Conservatory at Sunnycroft, a suburban villa in Shropshire owned by the National Trust, is what is probably the last in existence of the output of manufacturers R. Halliday & Co, employed by the Rothschilds to make the glasshouses at Waddesdon Manor in Buckinghamshire.

No 21, Aytoun Road, Glasgow, is in danger of demolition

Built in 1899 to house the owner’s ferns and replete with exquisite stained glass, it is a rarity. ‘The restoration required a combination of trades,’ says Pamela Smith, the Trust’s senior national consultant for gardens and parklands. ‘We commissioned surveys, appointed an architectural consultant and had someone to look at the glass, someone else at the ironwork. We also analysed the timber, which was Scots pine, and replaced it all, changing the design slightly.’

Elsewhere, Mother Nature plays a part. ‘It was a jungle!’ announces Lord Dunleath of the richly sculptural mid-19th-century conservatory at Ballywalter Park in Co Down, Northern Ireland, complete with elegant iron dome and parapet hewn out of golden-red sandstone. Until its renovation in 2009, this Classical work, added to the side of the house as a separate unit, was in a state of terminal collapse, suffering the erosive effects of the coastal weather and infestations of mice. Once chockful of plants and crammed with rockeries put in by his great-grandmother, the conservatory was cleared out, revealing hidden bases of plant benches, which were later reinstated. Crucially, ‘we commissioned a conservation architect and had advice from the curators at The Kibble Palace, the Botanic Garden in Glasgow,’ says Lord Dunleath, ‘and we restored, rather than replaced.’ Metalwork went to Yorkshire to be repaired, although sometimes compromise is needed: the windows now have toughened glass and new terracotta tiles replicate original colours.

‘Maintenance is crucial,’ says Roger Tempest of the mighty Andrews and Delaunay conservatory at Broughton Hall, North Yorkshire, assembled in 1855 and encircled by Nesfield gardens. A canny mutual arrangement meant the onion-like dome was restored by Oak Leaf Conservatories of York, which refurbished it in exchange for borrowing the structure for its display at Chelsea Flower Show. A strict schedule deals with the cleaning of this truly innovative building. ‘Water runs from the guttering down ornamental iron posts,’ adds Mr Tempest, ‘and straight into the soil like an irrigation system.’ Inside are passion flowers and grapes, even African lilies brought back from the Boer War by his grandfather.

The Andrews and Delaunay edifice of Broughton Hall, North Yorkshire, starred at Chelsea for its restorers, Oak Leaf Conservatories © Val Corbett/Country Life Picture

Ten years ago, the 1853 stone and cast-iron conservatory at Flintham Hall in Nottinghamshire, the country domain of Sir Robert Hildyard, built with its distinctive barrel-vaulted roof in striking homage to Paxton’s Crystal Palace, was added to Historic England’s Heritage at Risk Register. It was in a precarious state: ‘Bits of fatigued iron and cracked glass were dropping off,’ says Sir Robert, ‘and there was a fear it would collapse.’ Issues had been caused by water ingress and flawed ventilation, which had been altered over the years, as well as heat congregating in the barrel that created a summer temperature of 120˚C.

With the high level of humidity, it was very bad for the iron roof. Renovation involved the complete replacement of the top of the structure, including correcting previous restoration work. ‘It was beautiful once it was sanded and painted with seven or eight coats of paint.

Except for reinstating the old iron flower baskets on their pulleys and the tile work, we didn’t do anything to the interiors, rather left the old patina,’ adds Sir Robert. ‘Historic mass-produced conservatories also have their problems,’ advises Tom Massey of Dolmen Conservation and Joinery, now engaged in the repair of the Foster & Pearson glasshouses at the Chelsea Physic Garden in London, ‘especially issues with weathering and how water disperses with a modular system.’ Even the Victorians didn’t always get it right: the Grade II*-listed conservatory at Wentworth Castle, South Yorkshire, began rusting soon after it was assembled, probably in the 1880s by leading manufacturer Crompton & Fawkes of Chelmsford in Essex, complete with electric lighting. The revival of this rare ‘iron winter garden’ for the Wentworth Castle and Stainborough Park Heritage Trust in 2013 meant a kit-like dismantling of 4,000 pieces, the removal of every pane of glass and the replacing of 35,000 tiles.

Drainage was improved and rainwater harvesting introduced. ‘Now full of flowers from every corner of the globe,’ says Matthew Constantine, cultural heritage curator at the National Trust, current custodian of the site, ‘it is one of the star attractions, but its restoration was a miraculous recovery.’ Now that really is crystal clear.

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