The bricks that built Hampstead came, for the most part, from Hampstead itself. This is a fact so simple and so fundamental that it is easy to overlook, but its implications for the village's development, its landscape, and its architectural character are profound. For several centuries, the clay deposits that lay beneath and around Hampstead Heath were dug, processed, moulded, dried, and fired into the millions of bricks that form the walls of the houses, churches, and public buildings that define the area today. The industry that accomplished this transformation was, for much of its history, intensely local, its raw materials sourced from pits within walking distance of the construction sites they supplied, its workforce drawn from the village population, and its products incorporated into buildings that the brickmakers themselves could see from their yards. Hampstead, in a very literal sense, was built from its own ground.
The relationship between a place and its building materials is one of the most fundamental facts of architectural history. Before the coming of the railways, the cost of transporting heavy materials like brick and stone was prohibitive, and the buildings of any locality were necessarily constructed from whatever the local geology could provide. In areas of good building stone, houses were of stone. In areas of abundant timber, they were of wood. In the clay lowlands of south-east England, they were of brick, and the particular character of each neighbourhood's brickwork depended on the particular character of its clay. Hampstead's clay, shaped by the specific geological conditions of the Heath and its surroundings, produced bricks of a distinctive warm red-brown colour and a slightly irregular texture that remain visible in the oldest buildings of the area and that contribute immeasurably to the village's visual identity.
The Geological Foundation
The geology of the Hampstead area is unusually complex for a location so close to central London, and it is this complexity that created the conditions for brickmaking. The Heath sits on a ridge of high ground formed by the Bagshot Sand formation, a layer of sandy deposits laid down during the Eocene epoch, approximately fifty million years ago. Beneath the Bagshot Sand lies the London Clay, the thick, heavy, blue-grey clay formation that underlies much of the London Basin and that has been the principal source of brickmaking material for the capital since Roman times. Where the Bagshot Sand has been eroded or where the clay approaches the surface on the lower slopes of the ridge, deposits of brick earth, the specific mixture of clay, sand, and silt best suited to brick production, are found in quantities sufficient to support commercial extraction.
The brick earth deposits around Hampstead were particularly well-suited to the manufacture of high-quality building bricks. The clay contained a balanced mixture of minerals that produced, when properly fired, a brick that was hard, durable, and weather-resistant, with the warm colour palette that ranges from deep red through brown to a yellowish buff, depending on the precise composition of the clay and the temperature of firing. The presence of iron oxides in the clay was responsible for the characteristic red tones, while variations in silica content and firing conditions produced the range of colours that can still be observed in the brickwork of Hampstead's older buildings.
The topography of the Heath itself influenced the location and scale of the brick pits. The lower slopes and the areas around the edge of the Heath, where the London Clay came closest to the surface, were the principal sites of extraction. The higher ground, capped by the Bagshot Sand, was generally unsuitable for brickmaking, though the sand itself was used in the brick production process as a moulding material and as an ingredient in mortar. The result was a pattern of land use in which the Heath's fringes were pitted and scarred by extraction while its central areas remained relatively undisturbed, a pattern that has had lasting consequences for the Heath's landscape and ecology.
Brick Pits on the Heath
The brick pits that dotted the edges of Hampstead Heath were a defining feature of the landscape for several centuries, and their traces remain visible today in the undulations of the ground and the locations of several of the Heath's ponds. The ponds at the Vale of Health, for example, occupy depressions that are believed to have originated as clay extraction pits, their basins gradually filling with water after the cessation of digging to create the bodies of water that are now among the Heath's most attractive features. The Hampstead ponds on the eastern side of the Heath similarly owe their existence, at least in part, to earlier extraction activities, though their subsequent history as managed water features has obscured their industrial origins.
The process of extraction was straightforward but physically demanding. Workers dug the clay from the pit face using spades and mattocks, loading it into carts or wheelbarrows for transport to the brickyard, which was typically located adjacent to the pit itself. The clay was then weathered, a process that involved spreading it out and exposing it to frost and rain for a period of weeks or months, during which the natural forces of freezing and thawing broke down the lumps and improved the clay's workability. After weathering, the clay was mixed with water and worked by hand or by horse-driven pug mills into a smooth, consistent paste suitable for moulding.
The pits themselves varied in size from modest excavations sufficient to supply a single building project to substantial commercial operations that produced bricks for the open market over many years. The larger pits could extend over several acres and reach depths of twenty feet or more, creating dramatic scars in the landscape that were visible from considerable distances. The environmental impact of these excavations was significant. The removal of the clay and the overburden of topsoil and subsoil destroyed the original vegetation and altered the drainage patterns of the surrounding area. The pits attracted standing water, creating marshy conditions that persisted long after extraction had ceased, and the spoil heaps generated by the digging changed the contours of the ground in ways that are still evident today.
The relationship between the brick pits and the Heath was, inevitably, contested. The Heath was common land, subject to grazing rights and other customary uses that extraction activities disrupted. Disputes between brickmakers and commoners were a recurring feature of Hampstead's history, and the regulation of brick digging on the Heath was a persistent concern for the manor court and, later, for the vestry and local board. These disputes foreshadowed the larger conflicts over the Heath's use that would culminate in the campaign to preserve it as public open space in the nineteenth century, a campaign that was motivated in part by the desire to prevent further industrial exploitation of the land.
The Brickmaking Process
The manufacture of bricks in the Hampstead area followed the traditional methods that had been practised in England since the medieval period, evolving gradually over the centuries as new techniques and technologies were introduced but retaining its essential character as a skilled manual trade well into the industrial age. The process involved four principal stages: the preparation of the clay, the moulding of the bricks, drying, and firing, each of which required specific skills and equipment and each of which influenced the quality and character of the finished product.
After the clay had been extracted and weathered, it was prepared for moulding by a process known as tempering. This involved mixing the clay with water and working it to a uniform consistency, removing stones, roots, and other impurities that would cause defects in the finished bricks. In the earliest period, tempering was done entirely by hand, with workers treading the clay in shallow pits or working it with their hands on a flat surface. The introduction of the pug mill, a vertical cylinder containing rotating blades driven by a horse walking in a circle, mechanised the tempering process and produced a more consistent result, and pug mills were in use in the Hampstead area by the early eighteenth century.
Moulding was the most skilled stage of the process. The moulder worked at a bench, taking a lump of tempered clay of the correct size, dusting it with sand to prevent sticking, and pressing it into a rectangular wooden mould. The excess clay was struck off with a flat implement called a strike, and the moulded brick was turned out onto a flat board for transport to the drying area. A skilled moulder could produce several thousand bricks in a working day, and the speed and consistency of his work was a major determinant of the brickyard's productivity and profitability. The quality of the moulding, the pressure applied, the consistency of the fill, determined the regularity and density of the finished brick, and the best moulders were highly valued craftsmen whose skills were passed down through families and apprenticeships.
Drying was accomplished by stacking the moulded bricks in open-sided sheds called hacks, where they were exposed to air circulation but protected from rain. The drying period lasted several weeks, during which the bricks slowly lost their moisture and hardened sufficiently to withstand the heat of the kiln. The timing of drying was critical: bricks that were fired while still damp would crack or explode in the kiln, while bricks that were left too long in the hacks might begin to deteriorate. Brickmaking was consequently a seasonal trade, concentrated in the spring and summer months when the warm, dry weather provided the best conditions for drying. The Hampstead brickyards followed this seasonal pattern, their workforce swelling in the spring and contracting in the autumn as the weather turned.
Firing was the final and most dramatic stage of production. The dried bricks were stacked in a kiln, a structure that could be either permanent, built of brick itself, or temporary, constructed from the unfired bricks that were to be processed. A fire was lit at the base of the kiln and maintained for several days, gradually raising the temperature to the point at which the clay minerals fused and the brick became hard, dense, and impervious to water. The firing temperature, typically between 900 and 1100 degrees Celsius, and its duration determined the colour and hardness of the finished brick. Bricks closest to the fire emerged darker and harder, while those at the periphery of the kiln were lighter and softer. This variation, which modern brick manufacturers regard as a defect to be minimised, gave traditional brickwork its characteristic visual richness, the subtle variations in colour and tone that enliven the facades of Hampstead's Georgian houses.
Georgian and Victorian Brickworks
The expansion of Hampstead from a village of a few hundred inhabitants to a substantial suburb of several thousand was accomplished primarily in brick, and the local brickworks expanded to meet the demand. The Georgian building boom, driven initially by the spa trade and subsequently by the growing fashion for suburban living, required enormous quantities of brick, and the brickfields on the periphery of the Heath operated at full capacity during the building season. The standard Georgian house in Hampstead required between fifteen and twenty thousand bricks for its external walls alone, and the total demand generated by the construction of a single terrace of houses could run into the hundreds of thousands.
The Georgian brickworks were typically modest operations, run by individual master brickmakers who employed a small workforce of labourers and craftsmen and who often combined brickmaking with other building trades. The master brickmaker might also serve as a builder, contractor, or property developer, sourcing his materials from his own pits and using them in construction projects that he managed himself. This vertical integration was characteristic of the building trades in pre-industrial England, and it gave the master brickmaker a degree of control over the quality and character of the finished building that was lost when the production and use of bricks became separated into distinct commercial operations.
The Victorian period brought changes to the scale and organisation of the brick industry. The enormous expansion of London during the nineteenth century created a demand for bricks that far exceeded the capacity of local production, and the development of the railway network made it economically feasible to transport bricks over long distances. The Hampstead brickworks, which had been producing primarily for local consumption, found themselves in competition with large-scale industrial operations in Bedfordshire, Buckinghamshire, and the Midlands, whose mechanised production methods and access to superior clay deposits allowed them to produce bricks more cheaply and in greater quantities than the local yards could match.
The response of the Hampstead brickmakers was mixed. Some adapted, investing in new equipment and techniques to improve their productivity and reduce their costs. Others specialised, focusing on the production of high-quality facing bricks and architectural details that commanded a premium price and could not be easily replicated by mass-production methods. But many simply went out of business, unable to compete with the economies of scale that industrial production offered. By the end of the nineteenth century, the brick pits around Hampstead Heath had largely fallen silent, their clay reserves either exhausted or rendered uneconomic by the availability of cheaper alternatives from further afield.
Impact on the Heath's Landscape
The legacy of centuries of brick extraction is written into the landscape of Hampstead Heath in ways that are sometimes obvious and sometimes surprisingly subtle. The most visible evidence is the pattern of hollows, ridges, and water-filled depressions that characterises much of the Heath's lower ground, features that owe their existence to the removal of clay and the accumulation of spoil from the brick pits. These features, softened by vegetation and mellowed by time, have been so thoroughly absorbed into the natural landscape that most visitors to the Heath today would be surprised to learn of their industrial origin.
The Heath's ponds, several of which occupy former extraction sites, are perhaps the most significant landscape legacy of the brick industry. The chain of ponds on the eastern side of the Heath, which today serve as swimming facilities, fishing ponds, and wildlife habitats, developed in hollows left by clay digging. The water that filled these depressions came from natural springs and surface drainage, accumulating gradually as the pits were abandoned and the land reverted to a semi-natural state. The ponds have become such an integral part of the Heath's character that they are now protected as heritage features in their own right, their industrial origins acknowledged but their present value as amenity and habitat taking precedence over their historical significance.
The ecological consequences of brick extraction have also been significant. The removal of the original topsoil and the exposure of subsoil and clay created a mosaic of habitats that differed markedly from the original heathland vegetation. Some of the Heath's most botanically interesting areas, including patches of acid grassland and wetland, owe their existence to the disturbance caused by brick digging, which created conditions unsuitable for the dominant vegetation and allowed less competitive species to establish themselves. The ecological diversity that conservationists now work to protect on the Heath is, in part, a product of the industrial activities that they might instinctively regard as destructive.
Archaeological Evidence and Surviving Traces
The archaeological evidence for brickmaking on Hampstead Heath and in its surrounding area is extensive, though much of it requires expert interpretation. The most obvious survivals are the physical traces of the brick pits themselves: the hollows, embankments, and water features already described. More specific evidence includes fragments of kiln structure, accumulations of broken and misfired bricks known as wasters, and the compacted surfaces of brickyard floors, all of which can be identified by careful observation of the ground surface and, where excavation has been possible, by subsurface investigation.
The bricks themselves are, of course, the most abundant and most widely distributed form of archaeological evidence. The walls of Hampstead's older buildings contain bricks whose characteristics, their colour, texture, size, and the marks left by the moulding process, provide information about their origin and date of manufacture. Bricks produced in local kilns can often be distinguished from those imported from further afield by subtle differences in composition, differences that reflect the particular properties of the clay from which they were made. The study of these differences, known as brick petrology, is a specialised branch of architectural archaeology that has contributed significantly to our understanding of building practice and trade patterns in the pre-industrial period.
Documentary evidence supplements the physical record. Parish records, manorial court rolls, and the papers of individual builders and developers contain references to brickmaking activities, recording the names of brickmakers, the locations of their yards, the quantities of bricks produced, and the prices at which they were sold. Rate books and census returns provide information about the brickmaking workforce, its size, its composition, and its place within the broader social structure of the village. Together, the physical and documentary evidence allows a reasonably detailed reconstruction of the brick industry's history in the Hampstead area, from its earliest beginnings in the medieval period to its decline and eventual extinction in the late nineteenth century.
From Local Clay to Global Supply
The transition from local to industrial brick production in the Hampstead area mirrors a broader transformation in the English building industry, one that changed not only the way buildings were constructed but also the way they looked, felt, and related to their surroundings. When Hampstead's bricks were produced from local clay and fired in local kilns, each brick carried within it something of the place from which it came: the particular minerals of the local soil, the particular colour that those minerals produced when heated, the particular irregularities that hand moulding and wood-fired kilning inevitably introduced. The buildings made from these bricks were, in a geological sense, extensions of the landscape itself, their colour and texture harmonising naturally with the soil, the vegetation, and the light of the place because they were, quite literally, made from the same materials.
The industrialisation of brick production broke this connection. Bricks manufactured in the great Bedfordshire works, from the Fletton clay that underlay the Peterborough district in inexhaustible quantities, were uniform in colour, precise in dimension, and identical regardless of where they were used. They were also cheap, far cheaper than anything the local yards could produce, and their availability transformed the economics of building in ways that made local production increasingly unviable. The bricks that built the later Victorian and Edwardian extensions of Hampstead came not from the Heath but from the Midlands, transported by rail and distributed by merchant builders who had no connection with the local clay or the local landscape.
The aesthetic consequences of this shift were significant. The warm, varied, slightly rough-textured brickwork of Hampstead's Georgian and early Victorian buildings gave way to the smoother, more regular, and often harsher appearance of industrially produced brick. The difference is visible to any attentive observer who walks from the older parts of the village to the later developments on its fringes: a subtle but unmistakable change in character, from buildings that seem to grow out of the ground to buildings that have been placed upon it.
For those who work with historic brickwork today, whether in conservation, restoration, or sympathetic new construction, the Hampstead brick industry's history provides both a practical guide and a philosophical orientation. Matching the colour, texture, and character of original brickwork requires an understanding of the materials and processes that produced it, and in Hampstead this means understanding the particular clay deposits, firing techniques, and craft traditions that gave the village's buildings their distinctive appearance. More broadly, the history of local brickmaking offers a reminder of the relationship between buildings and their place, a relationship that industrialisation disrupted and that thoughtful contemporary practice seeks, in its own ways, to restore.
*Published in the Hampstead Renovations Heritage Collection — exploring the architecture, history, and stories of London's most remarkable neighbourhoods.*