In the footsteps of Alec Clifton-Taylor

A project to visit the buildings featured in Alec Clifton-Taylor’s classic ‘The Pattern of English Building’ leads to reflections on geology, building materials and photography.

Mud and thatch at Guilsborough, Northamptonshire. ‘The mud here is of a rich brownish ochre, the roof of good straw thatch’, Clifton-Taylor wrote. Photo by Robert Huxford.

1 Introduction
2 Photographing buildings
3 Understanding materials
4 The colour of brick
5 Related articles on Designing Buildings Conservation.

Introduction

Not another perforated pair of trousers, I thought, as the sheep dog sank its teeth into my left leg. I was on a public footpath that ran across someone’s back garden, hoping to take a colour photograph of one of the houses featured in Alec Clifton-Taylor’s The Pattern of English Building. The dog owner fortunately appeared on the scene, apologised profusely, and introduced me to his neighbour, the owner of the house in question. In return for blood-sacrifice I got the photograph and was able to take it from the exact position used for Clifton-Taylor’s original.

The Pattern of English Building was first published in 1962, with the fourth and definitive edition appearing in 1987, two years after Clifton-Taylor’s death. The book is a wonderful and thorough introduction to the materials that are the foundation of the character of English buildings and towns. The one thing the book lacks is colour. So for the past three years I have been travelling the land, trying to create a full set of the book’s 185 black-and-white photographs. During that time, I have gone from knowing nothing about geology and materials to knowing next to nothing – but keen to learn.

The task has been a delight. Passers-by are always very interested in the old photographs. Comparing the old with the new reveals common themes. One change is that, on the whole, the world has got greener. A fair few of the buildings have become obscured by foliage, hidden by hedges that have been allowed to grow out, or by tree planting. Sometimes this has been in the pursuit of privacy, other times it is due to cutbacks in maintenance. The number of cars and vans has multiplied. It can be difficult to photograph Clifton-Taylor’s more urban examples without there being vehicles in the view. In some instances, parked vehicles make it impossible to get into the position from where the original photograph was taken. Sadly, a proportion of the buildings have been lost to demolition. The cob-and-earth cottages are at particular risk. And losses continue: I missed by weeks the chance to photograph a run of flint cottages in North Norfolk.

Photographing buildings

I find architectural photography difficult. Representing a three-dimensional object in two dimensions is not something to be taken lightly. As we all know, parallel lines converge at infinity. If you stand directly in front of a building and look to the left, the lines point to the horizon. But worryingly, look to the right, and the lines point to the opposite horizon. How can this be? Is the building bent in the middle? I have a suspicion that our eyes practice a deception on us.

To get all of a building into a photograph, it may be necessary to angle the camera upwards, causing the verticals to converge dramatically. It is possible to use software to adjust for converging verticals, though verticals should converge just a little unless the photograph is taken from a distance. I find it challenging to create a photograph with angles that look right. Clifton- Taylor’s photographs are generally impressive; one wonders how they were taken, and what equipment was used. Some types of old bellows cameras permitted the lens to be tilted or shifted to remove distortion. Shift-lenses for 35 mm cameras became available only in the 1960s and they remain expensive.

Lenses also produce optical distortion that turns the straight lines of the real world into slightly curved lines. There are barrel distortion and pincushion distortion, and ‘moustache distortion’, which is a mix of the two. To a degree, this distortion can be corrected using software by hand and the more sophisticated packages can do this automatically.

Colour balance is another challenge. The colour of daylight changes according to cloud cover, atmospheric moisture levels and the angle of the sun, affecting the colour of the photographs. Professional photographers use white or neutral grey ‘photo cards’ to provide a reference and enable subsequent correction of the photos, but that is something for the patient person. There is also a debate as to whether or not to photograph in direct sunlight. Up to a point, if one does photograph on bright sunny days and avoid low sun angles, the colour balance question is largely resolved. But close-ups of stone and brick can look rather odd in direct sunlight, and because of the shallow depth of field in close-ups, it is easy to get things out of focus. Because we examine stone and brick surfaces close-up, our binocular vision can easily see the texture of the materials. In photographs that three-dimensional sense is lost: texture does not reproduce well. It would nonetheless be helpful if there were a library of photographs of brick and stone that would enable easy identification in the field.

The angle and position of the sun for a particular date, time and year, and the extent of shadows cast by nearby trees and buildings, can be ascertained using freely available websites (such as Shademap). This is particularly useful for planning when to photograph facades that face north.

Understanding materials

There have been tens of thousands of quarries and brickworks. Acquiring a knowledge of all these would be impossible. But sharing knowledge of the underlying processes by which materials and chemical compounds are formed and colours arise might help greatly. Stone is created by biological, chemical and physical processes. Igneous rock acquires different forms depending on how quickly it cools: rapid cooling leads to a uniform stone, whereas slow cooling gives time for large crystals to form. Clays are formed by weathering or chemical erosion of some of the minerals in igneous rock into sub-microscopic particles. Sandstone comes from the quartz component of igneous rock. The sorting effect of the flow of water, wave action or wind determine the stone’s grain size and texture. Chalk required the evolution of microplankton which formed calcite skeletons. With regard to colour, most materials are influenced by the absence or presence of iron compounds in their many different forms.

The stones of the British Isles go back as many as three billion years in the case of the oldest stones in Scotland. They are a record of the story of the Earth and provide insights into its future. Over that period there have been immense changes. The atmosphere has gone from having very low levels of oxygen and high levels of carbon dioxide, to what we have now. Levels of oxygen have been relatively stable for the past 500 million years. Temperatures and humidity levels have fluctuated widely, as have land and sea levels. The position of the land mass that formed England has changed too, owing to continental drift. A billion years ago, the English land mass was south of the equator but heading north. About 500–400 million years ago, a collision with the supercontinent of which Scotland was a part led to the raising of mountains perhaps as high as today’s Himalayas, that subsequently eroded into sand and clays.

Continental drift has taken England’s land mass through different climate zones that are driven by the Earth’s atmospheric circulation. There are three zones – the Polar circulation, the mid-latitude circulation and the ‘Hadley circulation’ at either side of the equator. It is here that the sun’s warming effect is greatest, heating the air, reducing its density and causing it to rise. Replacement air is forced towards the equator, bringing with it rainfall but drying the land on either side of the equator. The result is that the Earth tends to have deserts to the immediate north and south (though this can be strongly affected by the local land mass). This atmospheric circulation pattern is thought to have existed for several billion years. So as England’s land mass journeyed from south of the equator to where it is now, it passed through climate zones which form deserts south of the equator, swamps at the equator and more deserts to the north. Changes in climate, atmosphere, land mass, sea level, and the amount and form of iron present in the environment, have all influenced the appearance of the stone we see today.

Some sandstones were formed in a dry, desert-like environment. In the absence of water, they can be coloured with iron(III) oxide (FeO, ferric oxide), also found as the pigment Venetian red. As an example, 250 million years ago or so, what is now England was at a similar latitude to where the Sahara desert is today, and the sandstone that formed (New Red Sandstone) is coloured with iron(III) oxide.

Sandstone that is formed in a wet environment with iron present can be coloured with iron(III) hydroxide, which brings yellow to brown colours. Iron(III) hydroxide is found as the mineral limonite and as the main component of the pigment raw sienna. Examples are the sandstones of the Carboniferous period 360 to 300 million years ago, when Britain was in the vicinity of the equator. Iron hydroxide breaks down when heated above 200–300 centigrade to form ferric oxide, which explains why some yellow or buff stone acquires a pinkish blush when exposed to fire.

Initially I thought that this was a fairly conclusive and straightforward explanation for the colour of red and yellow stones. But I fear not, for red stones are also found in association with water, such as the remarkable red chalk of the Hunstanton Formation, in north Norfolk. There is more to find out.

The colour of brick

Bricks are remarkable things. It is astonishing that heat can turn clay, a weak, pliable material formed of sheets of atoms of aluminium, silicon, oxygen and hydrogen (and other elements) between four and ten atoms thick, into a highly resilient material that can support great weight and last thousands of years. But what is a brick? My impression is that much of the knowledge of bricks is based on chemical experiment and centuries of painstaking practical experience and empirical study: a certain clay when fired in a particular way will produce a certain type of brick.

But science continues to advance. There have been developments in scientific instrumentation such as X-ray diffraction, and new forms of spectroscopy which allow crystal and molecular structures to be examined and precisely identified. I sense that there is a deeper understanding buried in complicated academic papers that could be shared: what it is about certain clays and firing techniques that produce certain types and colours of brick. At the simplest of levels, brick is an artificial metamorphic rock, where under firing some of the constituent materials melt, gluing the structure together, and as the temperature increases other components start to form crystals, such as mullite (found on the island of Mull) and, at the highest temperatures, cristobalite.

Firing bricks in a reducing atmosphere (one that is short of oxygen) produces a blue brick. The colour comes from ferrous oxide (FeO, or iron[II] oxide). Firing in an oxidising atmosphere (where there is plenty of air) produces a red brick coloured by ferric oxide (FeO, or iron[III] oxide). This is what my father-in-law, former editor of the proceedings of the British Ceramics Research Association, told me. But this is not a sufficient explanation for the range of colours bricks actually have. Ferric oxide is a dull red, yet many of the most attractive bricks are orange. I find it hard to believe that ferric oxide can be the source of the colour. It surely cannot be iron hydroxide because, as we have seen from the Sherborne Abbey example, it breaks down at relatively low temperatures. There is not only ferric and ferrous oxide, but different phases of iron oxides with different molecular and crystal forms, along with more complex compounds with varied physical properties, which cause them to reflect and absorb different colours of light. Other elements may be involved, including manganese, vanadium, copper, aluminium, calcium, carbon and magnesium. There is much more that scientific methods could explain and enable us to understand.

Some bricks have a surface finish created by a sand applied prior to firing. Some are altered by other additives that act as a flux, causing the surface to change or melt, while others have a glaze. Clifton-Taylor was particularly interested in patterned brickwork such as at Chequers, in Rye, where the Flemish bond is picked out in grey headers. He uses the term ‘flared headers’, where, he says, the surface of the bricks has come into contact with the flames. But what actually changes? Examining one of the matt grey header bricks with a hand lens, one can see sand-sized translucent grey beads. What are they? Are they sand grains (quartz) that has slightly melted through wood fly-ash settling on the surface of the bricks and acting as a flux? There appear to be at least three broad types of grey header: one where the surface is matt; one where parts of the surface have vitrified and look glassy; and one where a glaze has been applied. These are only my suspicions. Definitive answers could be provided by scientific methods.

Another dimension affecting the appearance of buildings is the mechanical properties of locally available materials. There are regional patterns influenced by the scarcity or availability of wood or stone (see Region and Place: a study of English rural settlement by Brian K Roberts and Stuart Wrathmell). The span of wooden floor joists is limited by the strength of the wood, which is reflected in the width of rooms. Some local stones can be used as lintels and arches, but a wooden lintel will be required where the stone is rubbly and difficult to dress. This may then affect the position of upper-floor windows: whether they sit immediately below the wall plate, or further below the roof, with a run of stone above.

The Clifton-Taylor television programmes in the English Town Series (some are available online) show him to be someone out of the ordinary. His delivery is precise, his sentences short. His opinions are unequivocal: ‘Black or dark pointing is always ugly’. It is The Pattern of English Building of which he writes, and not ‘A’ Pattern of English Building. He shares his subject with enthusiasm and understated humour, never talking down to his audience, but freely introducing technical terms where needed, immediately followed by an easy-to-understand explanation. His subject is broad: from social, economic and industrial change, down to the practicalities of splitting stone or applying mortar. In barely four minutes he is able to recount the social and economic history of a town and explain why the buildings look as they do. He invites us into his world. We need to carry his enthusiasm, scholarship and concise communication into the 21st century.

What should we do? We should make use of the work that has already been undertaken, and extend it. The Strategic Stone Study and County Stone Atlases, produced by Historic England and the British Geological Survey, are a wonderful resource which should be referenced in every character statement and conservation area appraisal. The Strategic Stone Study could be augmented by including additional photographs that enable easy identification of stones in the field. A similar exercise should be undertaken to cover bricks and tiles: a Strategic Brick Study. And an equivalent of RW Brunskill’s Brick Building in England with colour photos is needed.

Streets, some of which still are paved with local materials, are vulnerable to industrial-scale highways maintenance, and at risk of being defaced by tarmac, and concrete kerbs and flags. The original Regional Streets for All series produced by English Heritage was an important step forward. It should be developed into a resource that documents in detail the materials and practices that are used at a regional and local level. There is no adequate source of information at the moment: only general principles, and limited advocacy.

We need building listings that are fit for the 21st century. Listings should contain enough information about a building to enable a fair attempt at its reconstruction, including photographs, precise descriptions of the materials and architectural details. In future photogrammetry and lidar would enable the creation of a digital twin of each building. A listing that asserts that a building is made of brick is not helpful when there are so many different types, sizes, colours and textures of brick.

We need to test the received wisdom and use science to fill in the gaps. Some of our understanding relies on the work of antiquarians who did not have the benefit of the scientific instrumentation available in the 20th and 21st centuries. Their views may have escaped the rigours of scientific and historical research. There may even be an oral tradition of knowledge. We are told that some buildings are built of Dutch brick, but does this really mean that the bricks are always from Holland? Perhaps some are actually bricks made in England by Dutch brickmakers. We are told that Dutch bricks were brought in as ballast: but is it really true that such a valuable commodity would have been treated as mere ballast? It is the same as suggesting that the Dutch would consider the wool products imported on the return voyage from England as ballast.

And there are many more questions to answer. How were black glazes seen on mathematical tiles produced? What is the cause of the orange in orange bricks? How is red rock formed underwater? Scientific instruments such as scanning electron microscopes, laser spectroscopy, x-ray diffraction and so on can provide answers.

This is not an endless task. There will be definitive answers to these questions. I hope that in future years a new edition of The Pattern of English Building can be produced which unites all of the disciplines involved, and makes the knowledge and wisdom of scientists, conservation professionals and craftsfolk available to all. And in glorious colour that celebrates the stunning beauty of brick, stone and the buildings of England!

Acknowledgements

Sincere thanks go to John Bennett (co-author of Bargate: the stone that built Godalming) for geological coaching and immense patience; to P. Meyer-Higgins for photographic advice; and to Rob Cowan for encouragement and continuing advice.

This article originally appeared in the Institute of Historic Building Conservation’s (IHBC’s) Context 181, published in December 2024. It was written by Robert Huxford, director of the Urban Design Group.

--Institute of Historic Building Conservation