On the night of April 12th, 2026, in the 1.4-acre walled garden at Hetherton Hall in north Norfolk, a 1924 cast-iron Dobby paraffin stove burned at low flame between the rows of espaliered nectarines and held the air temperature at the back wall of the lean-to glasshouse at 35 degrees Fahrenheit. The outside low at the nearest weather station was 27 degrees.
The stove was lit at 6:50 p.m. by the garden's keeper, an estate gardener named Tom Aldwick, with a long-stemmed match he keeps in a metal tin on a shelf above the door. The flame caught immediately. The stove had been serviced two weeks earlier.
The Dobby is one of three paraffin stoves still in regular use at Hetherton. The other two are a 1936 Aladdin and an undated Valor that may be slightly newer. All three are circular cast-iron units about 14 inches tall, with a brass fuel reservoir at the base and a chimney that vents through an asbestos-replaced flue stack.
Paraffin heating in walled gardens and lean-to greenhouses is, in 2026, an old technology approaching the edge of legitimate use. Modern frost protection is more often delivered by electric tube heaters, propane catalytic heaters, or hot-water radiator loops fed from boilers. The Dobby outlives them all by being repairable.
Tom estimates the running cost of the Dobby on a frost-protection night at roughly £1.20 for the paraffin consumed. The stove burns about a litre and a quarter of fuel over twelve hours at its lowest practical setting. A litre of greenhouse paraffin currently costs Tom 96p delivered.
The principle of paraffin heating is combustion, with the products of combustion vented to the outside. The Dobby's chimney rises through the roof of the lean-to via a sealed flange. The flue exits above the ridge and disperses to the open air.
This venting is important. Paraffin combustion produces water vapour, carbon dioxide, and small amounts of sulphur compounds depending on the fuel grade. None of these are welcome inside a closed greenhouse. The vented stove keeps the interior dry and the plants healthy.
There exist unvented paraffin heaters, sometimes called bottle-feed greenhouse stoves, which sit on the greenhouse floor and burn into the interior air. Tom does not use them and does not recommend them. The condensation, he says, will mildew a tomato in a fortnight.
The Dobby's heat output is modest. At full flame it generates roughly 1.8 kilowatts. At the low setting Tom uses on frost nights, perhaps 700 watts. In the 22-by-9 lean-to glasshouse against the south wall, this is enough to lift the air temperature by 8 to 10 degrees Fahrenheit above what the wall would hold alone.
The combination of stove and wall is the operating system. The wall, two feet of unrendered Norfolk brick, absorbs sun all afternoon and releases it through the evening. By midnight the wall alone, on a 27-degree outside night, would hold the lean-to at about 31 degrees Fahrenheit. The stove pushes the air to 35 and the nectarines do not freeze.
Frost on a nectarine blossom is, in early April, the difference between a crop and no crop. The bloom is held on year-old wood at the ends of the espaliered laterals. A single hard frost during full bloom can destroy 90 per cent of the fruit set. The stove exists to prevent this.
Hetherton's espaliered nectarines were planted in 1908 along the south wall of the walled garden. There are seven trees, of three varieties: Lord Napier, Pineapple, and an unidentified white-fleshed variety that may be Early Rivers. They produce, in a good year, around 240 pounds of fruit.
The stove is lit perhaps twelve nights a year, all in March and April, and a handful in October when the last of the late-fruiting plums are still ripening. Total annual fuel cost: under £20. Total annual maintenance: a half-hour wick trimming in February.
The Dobby's wick is replaced once every five years from a stock of spares Tom keeps in a small wooden box in the potting shed. The wicks were last manufactured in 1968. There are enough in the box, by Tom's count, to last another thirty years.
When the wicks are gone they will be gone. There is, as of 2026, no manufacturer producing replacement wicks for the 1924 Dobby. Tom is aware. He has, he says, made his peace with it. The stove will outlast him in any case.
The arguments against paraffin heating in 2026 are real. The carbon footprint of a litre of paraffin is roughly 2.5 kilograms of CO2. Tom's Dobby on a single frost-protection night emits about 3 kilograms. Over a twelve-night season, 36 kilograms. Over a decade, 360 kilograms.
This is a modest household figure but it is not zero. An electric tube heater run from grid electricity would, in the current UK fuel mix, produce roughly the same emissions. A heater run from rooftop solar with battery storage would produce essentially none.
The Hetherton estate has not yet installed solar capacity at the walled garden. The estate manager has it on a five-year plan. When the panels are installed and the battery is connected, the Dobby will likely retire to a shelf in the shed.
Tom does not expect this to happen during his tenure. He is 61 and intends to retire in 2031. The stove, he says, will see him out.
What the Dobby represents, on the warm April evening of its lighting, is the working life of a tool that has not changed in 102 years. The cast iron is unbent. The brass is polished. The wick is trimmed. The flame is steady. The nectarines are alive. The garden goes on.