Time for a windows upgrade
For Tim Maxwell, inheriting the listed glasshouses at Felton Park in Northumberland was a challenge
When we bought Felton Park in 2010, we didn’t pay much attention to the decaying, 90ft by 30ft curvilinear greenhouse at the far end of the garden, even though its Grade II* listing showed that the experts thought it more architecturally important than the house itself. erected in the 1830s and leaning against an older stove wall, the curves gave it a certain dilapidated elegance, with a fine patina of rust, despite having some 25% of its 9,000 fish-scale glass panes missing. Inside were two magnificent camellias and an out-of-control vine, quite unconcerned about the ruin around them.
Our first winter, 2010/2011, changed all that. The weight of snow and continuous frost took its toll. Another 10% of the glass was loosened and cascaded down the roof. Moreover, as the glass gives the structure its rigidity, stability became an issue. We’d reached a tipping point: either pull it down for safety reasons or restore it.
help was at hand. historic england had been monitoring the building for many years with growing anxiety, assisted by northumberland’s most experienced and well-regarded conservation architect, Robin Dower. If we would contribute to the restoration, historic england would too—and generously.
With funding agreed in principle, we were suddenly on the spot. how exactly do we go about this? The historic england network was activated both to find comparable restoration experience and to establish exactly how unusual this building was. The answer to the latter was ‘very’; only four or five strictly comparable lean-to curvilinear greenhouses survive.
We also went back to the man who had first designed this type of greenhouse, John Claudius Loudon (1783–1843). he is one of the great heroes of early-19thcentury urban and garden design. he was also a prolific writer. his Greenhouse Companion of 1824 goes into minute detail about the construction of curvilinear greenhouses, even specifying exactly the optimum overlap of fish-scale glass panes, a detail that turned out to be of great importance.
There was something of a greenhouse craze in the 1820 and 1830s, prompted in part by the arrival of exotic plants from all over the empire and in part by general interest in horticultural ‘improvement’, the whole stimulated by the competitive gardening world of the gentry. These factors coincided with manufacturing developments. The forging of slender, curved wroughtiron glazing bars, allowing in so much more light than heavy cast iron or wooden bars, only became possible in about 1815.
Apart from its aesthetic appeal, curvature, it was believed, allowed the warmth of the sun to better penetrate the glass. Loudon licensed his design to at least three metal forgers. To meet demand, they developed a mass-production system. The cast-iron frame and casements and the wrought-iron glazing bars were made to standard size and sent to the client, perhaps not quite as a ‘flat pack’, but certainly as a kit of parts. The manufacturers presumably didn’t have the effrontery to mark the consignment ‘easy Self Assembly’.
having worked out what was done in the 1830s, we were better positioned to work out what was required now, but, even so, we decided to do a test restor-
ation of a square yard of glazing a year in advance to avoid surprises. In fact, there was one surprise: we did the trial restoration in October and, by the end of November, blue tits had eaten at least half of the linseed putty. That put us on notice that the restoration had to be completed and the putty protected well before winter.
We now knew what we had to do, but then the tenders came in. That wasn’t a good day—we were far short. However, the fates were kind. The Heritage Lottery Fund and the Country Houses Foundation, the latter a private charity, both agreed to supply further funding, which got us to the target, but allowed for no mistakes or overruns. The final price was 0.11% under budget, a result seldom achieved in restoration projects.
There is always a point in any restoration when aesthetic judgments have to be made; it’s not always possible simply to copy the original. With the greenhouse, it arose over glass. The greenhouse had been re-glazed many times over the past 180 years. Glass is fragile and both technology and horticultural best practice change; plant scorching, for example, can be a problem under plain glass.
For the most part, the greenhouse had narrow reeded panes, but these are no longer manufactured. Fortunately, we were able to locate a source of second-hand reeded glass, with, importantly, a provenance. This met about half our requirement. We therefore decided that this glass should be saved for the roof and the casement windows and each gable end would be glazed with imperfect glass.
Glass is one of the few products in which the imperfect is more expensive than the perfect. We had to go to Lamberts Glass Works in Bavaria to find the genuinely faulty. Despite the cost, this was the best decision we made. The glass has a vitality that animates the whole building.
The work is now complete. We’re now planting up with citrus trees and peaches and trying to house-train the vine. The camellias’ internal thermostats have gone awry and we have flowers in December—only an adjustment phase, we hope.
To find out more about the greenhouse, its restoration and opening times, visit www.feltonparkgreen house.org
‘Despite the cost, this was the best decision we have ever made’
The greenhouse, with its elegant curved roof, follows closely the design developed by John Claudius Loudon from 1817 to 1820. The width and spacing of the glazing bars and the fish-scale design of the glass are precisely as Loudon recommended in his 1824 book, The Greenhouse Companion
The structure is 90ft long and 20ft wide and was built against the south-facing wall in order to receive maximum sunlight. On the other side of the wall is a spacious potting shed and, in the distance, you can see a glass partition. Protected from the weather, the old partition contained the earliest surviving glass