CLAY BATS AND CLUNCH BLOCKS

Shelford cottages

1.    CLAY BATS

         This story goes back to the very beginning of the 19th century, and a vicar. The curate of Hinxton was a great walker, and it was his habit to walk into Cambridge from Hinxton. Walkers have plenty of time to stand and stare, and one of the things that caught Parson Plumptre’s interest was a cottage which he spotted on the corner of London Road and Woollards Lane.

         Now clay bats and clunch are constantly confused in people’s minds, so here I want to pause and assert that they are totally different things. The clay bat is an unbaked brick, made of clay, worked in with straw, which has been dried in a mould. The ones I have seen are a cream colour, they are dry and powder easily to dust, and, of course, you’ll find bits of straw in them. Clay was dug from a handy local spot, mixed with straw and dried in the sun. Once dry the bricks could be used like ordinary bricks. The finished building was often rendered over, as clay bats are durable only as long as they don’t get wet. The advantage of clay bats over lath and plaster (the traditional timber framing material which was used in the older buildings in the village) is that wood, which is an expensive commodity, was not required. This made it an ideal material for someone who didn’t have much money. Clay bat is essentially the same material as Devon cob.

         Clunch, by contrast, is a block of chalk, the chalk a slightly harder than usual variety. It occurs naturally in South Cambridgeshire and has been used here and there about the village as a building material.

        Now let’s return to Parson Plumptre. The parson spotted a poor man in the process of building himself a slightly unusual cottage. That poor man was Joseph Austin, a Shelford bricklayer, and he had invented these clay bricks, or bats, for himself, in order to build himself and his family a home. The parson was much taken with Austin and his cottage, which Austin had first started in 1791. It had a very flat tiled roof, which projected a good way over the walls. This was obviously to keep the rain off, given the bats’ vulnerability to water. A “thin coat of clay” was used to render it. We have no picture of Austin’s original cottage, so we don’t exactly know what it looked like; after multiple extensions and improvements it would evolve into the pub which later stood on the site – the Road and Rail, with its adjoining cottages.  But historic buildings consultant, John McCann, believes that Austin was the first person to use clay bats in Cambridgeshire. From that point on, clay bats seem to have proliferated in Shelford, mainly used for cheap cottages, outbuildings and walls. Joseph Austin and his brothers were all bricklayers; perhaps, having trialled the technique, they rolled it out on builds for other people.  The next generation of Austins, also builders, continued the family tradition. Later in the century, with the arrival of the railway, cheap bricks came to the village, and from the end of the 19th century onwards small cottages were mostly built of brick. However, it was not uncommon for builders to use bats here and there, where it didn’t show, to economize on bricks. My own house is a good example. Built in 1904, the exterior is brick, apart from the first storey at the rear, where clay bats have been used and rendered.

         In the 20th century a lot of the clay bat cottages were allowed to deteriorate, and demolished in waves of slum clearance, but a few still survive, not to mention one of the very few grade 2 listed garden walls, in Tunwells Lane!

         Here is a gallery of photographs of clay bat cottages and other structures around the village, some still in existence, others demolished. Two things are diagnostic in identifying clay bats: one is rendering, the other a brick or pebble foundation layer, often painted black.

2.    CLUNCH

         Parts of Great Shelford, particularly at the eastern end of the parish, lie on chalk. Clunch is a hard form of chalk, found in the Middle Chalk, more formally known as Totternhoe stone. Clunch in Great Shelford is found on the outliers of the Gog Magog Hills, on the top of Granhams hill. It lies over impermeable chalk marl, and so springs emerge there too. One such spring, on Granhams Farm, feeds into what becomes the Nine Wells brook.

         Clunch was an important item in the village economy. There was already a village clunch pit in the 1700s. It is marked on a map belonging to St John’s College, dated to about 1790, and lay between Granhams Road and Hinton Way, on a track that has now disappeared.

         At Enclosure in 1835 an area of just over 2 acres was allocated to the parish Surveyors of Roads as a clunch pit. This now-disused pit sits on the crest of the hill on Granhams Road, on the left hand side.

         There are a number of clunch walls at Rectory Farm – in the tithe barn, and also some boundary walls. 

         Whitehill Farm was built some time between the 1835 Enclosure and 1871 when it first appears in the census, and was built of clunch.

3.    CLAY, CLUNCH AND GRAVEL PITS

         Just now I mentioned the Enclosure and the clunch pit. In the Enclosure Award a clay pit, a clunch pit and a gravel pit were all awarded to the parish. I was interested to discover that, even in 1928, these resources were apparently still, by right, open to villagers. On February 2 1928 the Parish Council agreed the rental of part of the clay pit to Cambridgeshire County Council as a depot (was this the beginning of waste collection, or “scavenging” as it was then known?), provided no hindrance was put in the way of any parishioner who wishes to dig clay.  So presumably, when building the clay bat cottages, villagers were able to come and get their clay at no expense beyond its transporting.

4.     SOME ADVICE IF YOU OWN A HOUSE MADE OF CLAY BATS

         Clay bats are a natural material and need to breathe. This means that, when they are rendered, they need to be coated in lime render, NEVER a cement one. Using a cement-based render leads to problems of damp inside the house. Once you’ve applied it, it’s very difficult to remove it again. Many builders are not familiar with clay bats, so use a professional who can work with lime. Or do it yourself. It’s quite possible. I know, because I’ve done it! You can find advice on what is involved here

www.limestuff.co.uk/pages/user-guides 

5. LIST OF CLAY BAT STRUCTURES IN GREAT SHELFORD

86 – 90 High Street, built early 1850s (by Watson Taylor)

20 – 30 Tunwells Lane (originally 9 cottages), built early 1850s (by Watson Taylor)

2 – 4 High Street (demolished)

49 Woollards Lane, The Orchard, originally cottages (demolished)

Barn at The Laurels (demolished)

Wall on south side of Old Thatch, along conservatory

26 – 30 High Street, back wall, upper storey and internal walls

Hills View

Garden wall on the drive up to 20a and 20b High Green

Garden wall behind the Post Office (rear of no. 18, side of no.16), which is listed

Garden wall along drive to no. 11 Hinton Way (Oakfield)

The Railway Tavern (demolished), built about 1847 by Rd Headley

If you know of any more, please let me know.

Sources

John McCann, Journal of the Cambridge Antiquarian Society, ‘The First Cottage of Clay Bats?’ (1987, vol 76 pp113-121).

James Plumptre, Society for Bettering the Poor, 1801, “Extract from an account of a cottage at Shelford in the county of Cambridge”.

© Helen Harwood, February 2021