• Grid reference: TL03572756
  • x=503570
  • y=227560
  • 51°56'13"N; 0°29'36"W
  • Civil Parish: Sundon, Bedfordshire

Clinker manufacture operational: 1899-1976

Approximate clinker production: 5.9 million tonnes

Raw materials: Grey Chalk (Zig-zag Chalk Formation: 94-97 Ma) and Chalk Marl (West Melbury Marly Chalk Formation: 97-100 Ma) obtained from common faces in pits successively further from the plant:

  • 503900,227500
  • 504100,227400
  • 504200,227100
  • 504150,226750


  • 1898-1900 B. J. Forder
  • 1900-1911 B. J. Forder and Son, Ltd
  • 1911-1976 BPCM (Blue Circle)

Often called Forder’s Works. The Forder organisation was the nucleus of what became London Brick, and lime plants and major brickworks were already under way. A hydraulic lime plant had been established around 1885 to the north at 503730,227950, exploiting the local 3 m bed of Totternhoe Stone. The cement plant was set up in 1898 with six chamber kilns (150 t/week, 16.1 MJ/kg), and started production in mid-1899. In 1899 a further eight chamber kilns (200 t/week) and in 1901 a set of four Schneider kilns (300 t/week, 10.5 MJ/kg) were built. After the experimental rotary kiln A1 (see article), half of the static kilns were decommissioned and rotary kiln A2 was installed on the site of chamber kiln 8: A2 was the largest kiln in Britain until it was overtaken by Wouldham B9 in 1912.

Read a description of plant in 1913.

It took some time to obtain satisfactory performance, but by the BPCM takeover both rotaries were working well and the static kilns were used only intermittently. The Schneider kilns were last used in 1924 and the chamber kilns were last used in 1928, although both remained in place until the closure of the plant. Kiln A1 was removed when kiln A3 was installed in 1928. The kilns were fitted with slurry sprays during the 1930s, but these were removed before the end of the decade, chain systems having been found to be more effective for heat exchange. From 1912 until the installation of efficient kilns for 1957 onwards, it was more or less unchallenged as lowest-cost plant. The plant survived the construction of Northfleet, when the nearby much larger Dunstable was closed, because of its very low manufacturing costs, but this advantage disappeared with the energy crisis, and its closure was part of the first phase of post-1973 contractions. The plant had a siding on the Midland railway, and used it for coal and gypsum deliveries up to closure. The plant was demolished, but all plans for redevelopment came to nothing, and the plant site and quarries remain waste land, with much of the foundations still visible.


The plant had a single washmill followed by two screeners.

Three rotary kilns were installed:

Kiln A1

Supplier: FLS
Operated: 12?/1905-1928
Process: Wet: a Polysius slurry dryer was added in 1938, but was removed around 1943.
Location: Hot end 503528,227545: Cold end 503546,227545: entirely enclosed.
Dimensions: Metric 18.00 × 1.800
Rotation (viewed from firing end): anti-clockwise.
Slope: ?
Speed: ?
Drive: ?
Cooler: Cooler pit, elevator and vertical 3 m i.d. drum cooler.
Cooler profile: ?
Fuel: Coal
Coal mill: indirect: ball mill
Exhaust: direct to stack.
Typical Output: 1905-1910 27 t/d: 1910-1928 30 t/d
Typical Heat Consumption: 1905-1910 11.1 MJ/kg: 1910-1928 10.3 MJ/kg

Kiln A2

Supplier: Edgar Allen
Operated: 1909-11/07/1976
Process: Wet: a
Location: Hot end 503529,227535: Cold end 503575,227536: hot and cold ends enclosed.
Dimensions: 150’0”× 8’6”B / 7’6”CD (metric 45.72 × 2.591 / 2.286)
Rotation (viewed from firing end): clockwise.
Slope: ?
Speed: ?
Drive: ?
Kiln profile: 0×2286: 2007×2286: 3226×2591: 9931×2591: 11151×2286: 45720×2286: Tyres at 1588, 11087, 19355, 30861, 42164
Cooler: rotary 61’3”× 4’6” (metric 18.67 × 1.372) beneath kiln
Cooler profile: 0×1372: 18669×1372: Tyres at 3658, 15850
Fuel: Coal
Coal mill: ?: later direct: No16 Atritor
Exhaust: initially direct to stack. An ID fan was added in the 1930s and an APCM "Unit" electrostatic precipitator was added after the fan in the 1960s.
Typical Output: 1909-1910 83 t/d: 1910-1928 112 t/d: 1928-1933 126 t/d: 1933-1942 155 t/d: 1942-1951 148 t/d: 1951-1962 163 t/d: 1962-1976 151 t/d
Typical Heat Consumption: 1909-1910 9.2 MJ/kg: 1910-1928 8.3 MJ/kg: 1928-1933 7.8 MJ/kg: 1933-1951 7.6 MJ/kg: 1951-1962 7.83 MJ/kg: 1962-1967 8.23 MJ/kg: 1967-1976 7.85 MJ/kg

Kiln A3

Supplier: Edgar Allen
Operated: 1928-29/11/1976
Process: Wet, initially with slurry sprays.
Location: Hot end 503530,227528: Cold end 503575,227530: hot and cold ends enclosed.
Dimensions: 150’0”× 8’6”B / 7’6”CD (metric 45.72 × 2.591 / 2.286)
Rotation (viewed from firing end): clockwise.
Slope: ?
Speed: ?
Drive: ?
Kiln profile: 0×2280: 2648×2591: 9957×2591: 12852×2286: 45720×2286: Tyres at 1505, 11138, 19704, 30944, 42183
Cooler: rotary 61’4”× 4’6” (metric 18.69 × 1.372) beneath kiln
Cooler profile: 0×1372: 18694×1372: Tyres at 2997, 15646
Fuel: Coal
Coal mill: direct: initially Clarke Chapman Turbo Pulveriser: later No16 Atritor
Exhaust: initially direct to stack. An ID fan was added in the 1930s and an APCM "Unit" electrostatic precipitator was added after the fan in the 1960s.
Typical Output: 1928-1933 130 t/d: 1933-1942 161 t/d: 1942-1951 147 t/d: 1951-1962 163 t/d: 1962-1976 154 t/d
Typical Heat Consumption: 1928-1933 7.8 MJ/kg: 1933-1951 7.6 MJ/kg: 1951-1962 7.91 MJ/kg: 1962-1967 8.41 MJ/kg: 1967-1976 7.86 MJ/kg

Sources: Cook, p 43: Francis, pp 210-211: Jackson, pp 259, 279, 299: Pugh, pp 270: "Sundon Cement Works, Harlington, near Dunstable", The Engineer, CXVI, p 167.

Read the Engineer article.

Read The Engineer at Grace's Guide.

The following is a transcript of an anonymous article that appeared in The Engineer, 116, 15 August 1913, p 167. It is believed to be out of copyright. It describes the Sundon plant after the installation of the second rotary kiln, which was the largest kiln in Britain at the time of its installation.

Values of imperial units (as of 1918) used in the text (alphabetical order): 1 acre = 0.40468424 Ha: 1 ft = 0.30479947 m: 1 gallon = 4.5460756 dm3: 1 HP (horse-power) = 0.7456998 kW: 1 inch = 25.399956 mm: 1 psi (pound-force per square inch) = 6.89478 kPa: 1 ton = 1.01604684 tonne: 1 yard = 0.91439841 m.

Sundon Cement Works, Harlington, near Dunstable

The works of this firm, which is associated with the British Portland Cement Manufacturers, Limited, are situated at Harlington. about 15 miles from Bedford and 5 miles from Luton.

The works were first constructed with 14 Johnson chamber kilns, but in 1901 Schneider kilns were erected, the flues of the chamber kilns being roofed in and covered with cast iron plates to provide a floor to dry materials for the Schneider kilns. In 1902 (Note 1) an American rotary kiln, 60 ft. by 6 ft., was installed by F. L. Smidth and Co., of Copenhagen, and in 1908 (Note 2) an order was placed with Edgar Allen and Co., of Sheffield, for a rotary kiln 150 ft. long by 7 ft. 6 in. diameter.

The manufacture of cement at these works is carried on progressively in the following order:

From the chalk quarry the materials consisting of chalk and marl (mixed in the necessary proportions determined by chemical analysis) are conveyed to the wash mill by an endless chain hauling gear (Note 3). Here they are fed through rolls into the mills, where they are washed through gratings and elevated to the wet mill. This contains three sets of Clarke's mills, through which the slurry passes into the mixers by gravity. From the mixers it is distributed to the rotary kiln slurry storage tanks by Taylor's three-throw pumps, and then it is pumped direct into the kiln through reducing nozzles. The No.2 kiln, installed by Edgar Allen and Co., Sheffield, is 150 ft. long by 7 ft. 6 in. diameter, with an enlarged burning zone 8 ft. 6 in. diameter (Note 4). The heat given up by the clinker as it passes through the cooler is used to dry the coal (Note 5). The clinker is delivered on to a shaker conveyor and then elevated and conveyed direct to the grinding plant or storage ground. In the grinding plant the clinker, after passing through steel roller crushers, is elevated to storage bins, where it passes by gravity to the Kominor Mills. Here it is prepared for the tube mills, which do the final grinding. It is then elevated and conveyed to a cement warehouse, which consists of a series of bins each of 1000 tons capacity (Note 6). The power plant consists of two twin-cylinder and one single-cylinder gas engines by the National Gas Engine Company, developing 800 brake horsepower. There are seven suction gas plants. There is a well-equipped laboratory and testing-room, where the materials are tested at various stages of manufacture. The number of men employed at these works is about 150.


Note 1. As so often, this date is deceptive. The kiln was commissioned in 1905, and what is more, FLS list the order date as 1905 as well. It was No.52 on their list of rotary kilns supplied world-wide. It is referred to as "American" because, as with all the early FLS kilns, it was constructed largely to the specifications of Lathbury & Spackman.

Note 2. It was commissioned some time in 1909.

Note 3. The deposit at Sundon was physically divided between Grey Chalk above and Chalk Marl below by a 3-4 m band of Totternhoe stone. Both the Grey Chalk and the Marl varied more or less linearly in calcium carbonate content: the chalk varied from around 78% at the base to 88% at the top, while the marl varied from 77% at the top to about 60% at the bottom. In extracting the deposit, advantage was taken of this linear vertical variation by scraping the material with a harrow, from the top downwards, to form a fairly shallow sloped cut. As the thickness of the Grey Chalk varied, the length of the cut downwards into the marl was varied in order to keep the overall chemistry of the cut close to the target value (76%, rising in later years to 78.5%). This ensured that the material arriving at the washmill rarely varied from target chemistry by more than 1-2%. The reliability of this process contributed much to the success of the plant in the early years. Later, as the use of quarry faces worked by draglines and face shovel was developed, management of the quarry became much more complex.

Note 4. Kiln 2 was at the time of installation Britain's biggest kiln. The Swanscombe kilns had been lengthened to 130 ft in 1907, but the Sundon kiln had a greater diameter and had a rated output 30-50% greater. The kiln was Edgar Allen's first.

Note 5. Failure to recycle cooler heat to the kiln was a feature of many of the early kiln designs, and was a basic mistake made by Allen. The continental suppliers, as they introduced their own large kilns in the next few years, tried to use cooler air appropriately. The Sundon cooler air was later introduced into the kiln hood in the normal way, compensating for the very narrow cooler throat by pressurising the cooler.

Note 6. The six box-like cement bins, with extraction screws at the base into which the cement had to be persuaded by trimming from the front with long rakes and air-lances, remained a quaint feature of the plant until it closed in 1976. Concrete silos for cement began to be erected around 1910.