PINNER CHALK MINE - A QUICK TOUR
The excellent pictures were taken by Nick Catford in 1996. They will serve as an introduction to the mine while I am slowly, slowly finding the time to rebuild the website that was ‘lost’. The map, 1850 shaft, 1840 and ‘JG’ graffiti photos were provided by me.
Visits to the mine are not possible now as the London Borough of Harrow has closed it for Health and Safety reasons. In fact we had no accidents for the 34 years I was associated with visits. But there’s always a first time, I suppose.
The visiting group was limited to about ten, otherwise you spend too much time climbing down and up again. The escorted tour took up to an hour.
Looking up from the bottom of the 1850 shaft. On the right is the mountaineering ladder made of ESFSWR (extra special flexible steel wire rope). The aluminium rungs are 20 cm wide (enough for one person’s shoe) but 30cm apart. You keep the ladder close to your chest and then it is just a question of how fit you are! On the left is the safety rope which is attached to a strong belt (supplied by the access team). Team members then pay out the line as you descend. And keep it taut as you climb. And yes, we have had to pull a few people out! Ladies go down, and so do 80 year olds. But if you are over-weight you won’t even get through the manhole cover at the top!
Visible in the photo above is one of the secrets of the stability of the workings. It is a layer of Hertfordshire puddingstone which acts like a concrete roof over the chalk. Modern safety precautions would demand at least a metre of chalk in the roof, but the miners were able to leave just 30cm and thus increase the take of chalk. There is just one roof fall in the 1850/1860 workings. This is modern and caused by the workers installing (but dropping on the ground first) the heavy steel safety cover for the open manhole.
First we see the 1850s workings. The miners have started by excavating tunnels (headings) outwards until the wheel-barrow run has become too far from the bottom of the shaft and wastes time. Then they dig down another two metres near the bottom of the shaft, and this time a trench is started and continued as far as the first heading. Then they go back to the bottom of the shaft, and do the same again. This is how the roof of the heading is about six metres above the floor.
Notice how cleverly the miners have created a concave shape to the pillar walls. This not only cuts across any fault lines but increases the take from the mine. The Pinner mine is very efficient
in removing 65% of the chalk without making the mine unstable. Almost all of these 1850/1860 workings have not changed in 160 years.
The discolouration of the bottom foot or so of the pillars implies that at some time there has been a deluge up top, and rainwater has entered the mine before draining into the dry chalk.
The miners worked in two-man teams; one hewed the chalk while the other man filled and conveyed the barrow. At the foot of the shaft, the chalk would be loaded into a metal bucket called a kiddle
and raised to the surface by a geared winding mechanism, or for economy a small draught animal. Then the lumps of chalk would be taken to the kiln, and stacked waiting their turn for the 36-hour
There might be a small number teams so that they could be digging the side headings, and then open up another long heading parallel to the first heading. Below is another such heading. This time the discolouration probably comes from a torch being switched on which displays a light which is not white like a flash gun.
Mining the chalk was only a matter of a few weeks each spring. The leaseholder was a builder who only wanted enough chalk to make lime for that summer’s building work. Some chalk was for local farmers who stilled ploughed the land. The chalk would be left in the fields to break up over winter and then be ploughed in to lower the acidity.
In the next long heading to the right of the one above, the miners broke into the 1830 workings. Now these workings are messy (see next picture).
There are roof-falls allowing red running sand to enter the workings and then stabilise when a cone of sand has formed below the break. The walls are not curved, and show poor technique by following
fault lines rather than crossing them. It must have been tempting to insert the pick into a crack and pull down a large section of chalk.
We call them the 1830 workings because on the drawing accompanying the 1832 lease, it shows a shaft to the south east of the shaft we use. We call it the 1850 shaft because the nearest date to the bottom of the shaft is 1851.
Here is a typical view of the 1830 workings. The unstable walls; the slope of red running sand where a cone has formed; using a fault plane as the roof such that some close at hand vertical fault planes would render it unstable and liable to fall.
A miner has written his initials on the roof, but with the date of 1847. The combination of initials is very unusual, so it was easy to trace him in the 1841 Census for Pinner. He was Isaac Webb, a young agricultural labourer. His youthfulness, 19 in 1847, may account for the date being the second earliest to be found in the whole mine, and for writing it in the 1830s workings which had been abandoned by then. And he wants to make sure they can be read whichever direction you come from!
It is unclear why this section of the 1830s workings is so far north of the 1830 shaft. Was the chalk unworkable elsewhere? They would be underneath someone else’s property if they went outside the designated surface area which contained a quarry for clay and sand and some gravel. The quarry was a continuation of the Waxwell Lane diggings on the other side of the Uxbridge Road. The kiln was within the legally allotted site. It was up on a promontory at the original surface level so that the necessary updraught for the kiln fire was available. There was also a plentiful local supply of kindling for fuel.
Next we have a picture where two separate mines meet, and 20th Century graffiti provides some interesting local history.
We are standing in the northernmost extent of the 1830 mine. Straight ahead is a 30cm square peephole. This is where the miners working south from the 1840 shaft realised that their picks were getting a hollow ring to their blows. Step 1 - make a small peephole and have a look. Step 2 - make a man-size entry hole and step through. This is to the left of the peephole as we look at it.
What now for the 1840s miners? There are two short galleries running east and stopping before they are ‘outside’ their property. There are some possible workings to the north and west, but the start of any tunnel is now blocked by running sand. It would be problematic for us burrowing through to see whatever might be there. The effort required outweighs the thrill of being the first people to see the workings for 160-odd years. When miners left they took whatever was valuable with them.
Modern history gets a look-in by the graffiti GPY 1933. The initials GPY are significant. The Yarrow family lived in Blythwood House, immediately to the east of The Dingles quarry area. One of the
sons, Gordon Percy, was 16 at the time and ripe for exploration of the mines. They may well have learned about the mine from the surveyor from South Wales who came in 1930 to do a plan of the mine to
establish a safe building line for the houses on the south side of Norman Crescent. In World War II Gordon became a pilot. He was a Flight Lieutenant RAF when his Blenheim of 110 Squadron, Bomber
Command crashed in Cornwall after returning from an operational flight on 28 March 1941. He died of his injuries two days later, but the other two members of the crew survived. He was 24 years of
His father was one of the Yarrow family of shipbuilders up north, and he obtained some steel sheets to build a bungalow (prefab?) in the quarry area. Rumour has it that it suffered from condensation problems. We’ve never seen a photo of it.
The graffiti has been burned by a carbide torch or similar. You can tell this by the size and boldness of the characters and numbers. This graffiti will stay as of historic interest. Otherwise the aim is to leave the mines in the state that the miners left them in.
The miners had only candle light to work by, and they used the flame and soot to do their initials and dates. This could only be done while they could reach the roof which accounts for the writing four metres or so above our heads. As compulsory education did not start until 1972, it shows that labourers could do some writing. Some could not of course, as the various Xs in the Church Registers show when a signature was needed.
This perhaps uninspiring shot is looking up the 1840 shaft. At the top it is capped by a double skinned dome of bricks, held solid by a central ‘keystone’ brick, which is remarkably difficult to break into. This is the fate of many well-shafts; capped by a dome, covered with earth, and forgotten. The bricks are laid dry, as any mortar over time would decay and cause a collapse. Water can penetrate, so at times of heavy rain quite large puddles form nearby before very very slowly sinking into the chalk.
We leave the 1840 shaft, so-named because the first four miners to start digging the tunnel have burned their initials and the date 1840 in a list on the roof. The 1841 Census finds them living in Pinner. They are labourers who have found it convenient to hire themselves out for a short period as a gang, I imagine.
They are James Corbett, John Evans, Thomas Bugden, and John Smith. We would regard John Smith as a very common name now, but the most popular surname in Pinner at the time was Lawrence. Bugden too was a common name in the local area.
Their address was West End Cottages (much later known as Vine Cottages). These were between the modern Gloucester Cottage and Rose Cottage in West End Lane.
We go south for about 20 metres, enter the 1830 tunnels which are all at just one working height i.e. just enough room to swing a pick over the head. Then after about 40 metres we clamber down into the 1850 workings. We re-trace our steps to near the start of our tour where we step down a level to cut through to the 1860 workings. Before getting there, everyone is asked to turn off their lights. It is quite unusual to experience total darkness, and slightly unnerving. Obviously there is no sunlight underground, so absolutely no life can exist down there.
Close to the centre of the photo is half of an entrance gap (to go up a level again) to the 1860 main road level.
Chalk is an aquifer and when it was full of water it was obviously very damp! But when water extraction for the London industrial activity of the 1700s and 1800s exceeded the rate of fill by rainwater, the water table dropped. It was this drop and subsequent drying out of the chalk which allowed the chalk to be mined in the Thames basin. At the edge of the basin in the Chilterns and North Downs chalk had always been obtainable, although wet. The water table is rising again, and every night one of the Tube tunnels under the Thames has to be pumped dry.
Where it says ‘mines meet here’ in the map below, it is where you clamber up a slope to get to the 1830 workings from the 1850s. Where you step through from 1830s to 1840s is not shown. The hatch
marks indicate the quarry slope, but also conceal slightly the little circle for the 1850 shaft. From the bottom of the 1850 shaft you can turn south and go down various headings but they all finish
at roof falls with running sand. The 1830 workings also go north but they are blocked off at various points. At two places the 1850 miners broke through into these 1830 passages. The 1830 tunnels end
where they form the access route from 1850 to 1840 workings.
The 1860 workings are mostly to the north west of the 1850 shaft. These workings supplied the major part of the 15,000 tonnes total take of chalk from the mines.
[The words ‘Grim’s Ditch’ refer to what is on the surface above the mines. It’s a massive cut and fill construction where the ditch on the south side supplied the earth for the mound. This probably had a paling fence on top to increase the height.]
The kiln site is not shown on this map, but it was on that point of land on the western boundary shaped like an upturned nose.
Before Dingles Court was built, that piece of land had a pair of semi-detached houses dated about 1900 perhaps. In one of them lived Joseph Archer who gives his trade as Lime Burner in the 1861 and 1871 censuses. In 1881 he is an agricultural labourer, and in 1891 he gives General Labourer as his employment. You can almost feel the demographic change of life in Pinner as it progresses towards just an outer London suburb.
There are two adit mines under the allotments near the entrance. Adit entrances are ‘walk-in’ from the quarry floor. The mines are in a poor state, and responsible for the collapse noted.
Here we are at the last Nick Catford picture of this quick tour.
The visitor (let’s call him John) is standing on the main road of the 1860s mine. It’s called the main road because the barrows used it to take their loads to the bottom of the shaft. As you can
see there is one working level above and below John.
On the wall behind him there are five burn and soot marks from the candles which the miners stuck into a lump of damp clay and stood them on a convenient piece of projecting flint. Now look at the layer of flint on the side wall roughly in line with John’s shoulders. This is tabular flint. Because it is already slim, it is what prehistoric man would be looking for in shallow chalk deposits. Using another stone this flint can be ‘knapped’, This means striking flakes off the sides to create a cutting edge - a flint tool. The lines of flint above and below this layer are nodular flint; they are larger and rounder than tabular flint and would be used as a basis for foundations and walls when natural building stone or bricks were not available.
What is chalk? For simplicity’s sake we can say that plankton (which has vegetable and mineral content) formed the sea bed 65 to 145 million years ago. Over time this has solidified into chalk. At regular intervals a complicated process took place when the mineral remains all sank to a certain level and met the rising gases from putrefaction causing a chemical reaction which created silicon (flint). Under London the chalk is 200 metres thick.
The most prolific graffiti writer was John Gumm. There are so many JGs on the roof that he must have recorded each day's progress. He has also signed in for each year from 1855 to 1870. The list of properties in the Ruislip census for 1851 suggests that he was living in a cottage near The True Lovers' Knot Public House on the Rickmansworth Road. This is now a block of flats next to the off-road car park of Northwood Golf Club. He probably worked in the nearby gravel pits, chalk pits and sand mines of Northwood. His continuous presence at the Pinner mine implies some expertise and he must have become the gaffer.
John Gumm (or Gomm in earlier records) is in the Pinner 1861 census with his Pinner-born wife Eliza (Brotherton), both aged 33. He was born in Ruislip, and so were his three children William, Eliza, and Anne of 10, 7 and 5 years. They moved to Common Road (the modern Elm Park Road) in 1856. Emma born in 1858 died early, and John born in December 1859 died in September 1861. Why was Pinner so unlucky for them?
John Gumm signed in for the last time on April 28th 1870 (see photo). This is also the last year date in the mine and perhaps marks the end of a period when a local brick and tile maker could pay local men to dig and raise and burn local chalk. John Gumm is not in the 1871 or 1881 England and Wales census. Where did he go? The imagination runs riot. Digging for gold in North America or Australia? In the 1891 census he and his wife are living with their son in Alperton. Father and son probably both work in the local brickfields. JG dies on January 2 1909. He died of 'old age, asthma, and bronchitis', in the Hendon Workhouse. That's not as bad as it sounds; the final caring period would have been difficult at the small family home in Mount Pleasant, Alperton.
In the upper photo, his name and date is in full for 1869. But for the 1870 signing-in it is JG, then capital A for April 1870.
Elsewhere in the mine he has written Roton Row. We can forgive the spelling, he may not have gone to school. What we have found out in Pinner Local History is that various places were
given nicknames. The stretch of Potter Street from where it starts at Pinner Hill Road up to the high point at Lyndhurst Gardens, was known as Constitution Hill. If you stand on that corner you can
Where the Gumm family lived in Common Road (the modern Elm Park Road) was known as Rotten Row. No doubt because horse riders would be reminded of the elm-lined thoroughfare in Hyde Park.
© Ken Kirkman 2013.