SNN116840 - Archaeological Excavation: The Glasshouse within the Walled Garden, Althorp

In May 2023, Archaeology Wales Ltd conducted an archaeological evaluation on the remains of a glasshouse located within the Walled Garden on the Althorp Estate. The site was centred on NGR SP 68350 64549, Event Number ENN111441. The excavation was conducted prior to planning permission being sought to reinstate the glasshouse. The excavation of Trench 1 revealed that the foundations and subterranean structures associated with the glasshouse survive well beneath the ground. The structure had clearly expanded over time, with two earlier phases of glasshouse evident at either end of the structure, with a later building constructed between these to form a single glasshouse. Within this later addition the floor levels survived sufficiently to show that the central section of the glasshouse had been split into three separate pine pits, with a number of flue outlets for the heating pipes recorded around the pits. Ancillary structures were recorded along the exterior of the north-western wall of the glasshouse, which would have likely accommodated potting sheds, tool stores and worker rest rooms. The subterranean structures below these rooms provided access to the furnaces that needed to be constantly fed in order to supply the house with enough heat to grow the exotic plants, such a pineapples. Later boiler rooms show the change from these hot air furnaces to a hot water heating system. Within Trench 2 the remains of a backfilled pond were recorded. The pond had been used to feed water up into the Walled Garden through a ram pump. Part of the pumping system was found, with a cast iron pipe running up from the base of the pond towards the Walled Garden.