Irthlingborough Ironstone Mine

Overview

The largest underground ironstone mine in a county otherwise defined by opencast working — a Welsh steelmaker's answer to overburden it could not afford to strip, reached by a three-quarter-mile tunnel driven into the Nene valley and worked by pillar-and-stall under an electrified overhead railway.

History

The Ebbw Vale Steel, Iron and Coal Company began taking Northampton Sand Ironstone at Irthlingborough by open quarry in 1915, the date still cut into the brick arch of the mine entrance as "EV 1915". Quarrying alone could not follow the bed far, and from 1918 the company committed to driving a full underground mine instead. Labour was a running problem from the start: 55 people were employed by June 1916 and 91 by the end of that year, and in June 1917 fifteen Cornish miners were brought in, most of whom stayed only about eight weeks. By the time the mine proper opened in 1920 some 150,000 tons of ore had already gone west to the Ebbw Vale furnaces. Richard Thomas and Company bought the operation in 1935 and extended the main tunnel through to the Finedon quarries in 1938; from 1945 it ran as part of Richard Thomas and Baldwins Ltd. In 1951, with the mine still working, the Ministry of Works surveyed it for the Central Register of Underground Accommodation and reserved it as possible storage for museum and art gallery collections — the report assessing its access, ventilation, services and resistance to different types of bomb.

Geology

The ore is the Northampton Sand Ironstone, a Middle Jurassic bed of ooidal ironstone laid down in shallow marine conditions and worked as a single seam rather than a vein. It is a low-grade ore by international standards, and its economics depended entirely on being cheap to win and close to a railway. That is the key difference from the haematite bodies of west Cumbria: this is a sedimentary bed of fairly consistent thickness that can be followed flat for miles, not an irregular replacement mass. At Irthlingborough the bed lies only around 60 to 80 feet below the surface near the mine entrance, but under enough limestone and clay cover that stripping it was not worth the cost — the reason a Northamptonshire ironstone operation went underground at all.

Geological setting: Sedimentary Beds and Seams (well documented example)

Workings

The mine was entered by a brick-arched adit driven from the Nene valley, the main tunnel running about three-quarters of a mile at a rising gradient of 1 in 210 so that loaded traffic ran downhill to daylight. Two shafts 13 feet in diameter and 1,100 feet apart were sunk to let the tunnel be driven from several faces at once, No. 2 shaft afterwards serving for ventilation. Extraction was by pillar-and-stall, the seam taken in rooms with pillars of ironstone left standing to hold the roof. Haulage was by a 3 ft gauge railway electrified from an overhead wire at 250 volts — two four-wheel electric locomotives supplied by GEC in 1938 and six more by Greenwood and Batley in 1941, of 240 to 260 horsepower. At surface the ore was calcined in a bank of kilns and passed by tramway to the Northampton and Peterborough branch line. By its later years the system had two entrances some two and a half miles apart.

Closure

Sources differ slightly on the end date. The Coal Authority's abandonment plans for Irthlingborough are dated 30 September 1965, while the separate Richard Thomas and Baldwins plan of the Northampton Sands ironstone mine is catalogued as abandoned in 1966 — the difference most likely between the last working of one district and the final formal abandonment of the whole take. Either way the mine did not long outlive the Northamptonshire ironstone industry generally, which collapsed through the 1960s as British steelmakers moved to richer imported ore that could be landed at deep-water terminals more cheaply than a low-grade Jurassic seam could be mined at home.

What remains

The mine is sealed. The tunnel entrance was bricked up after closure, and no exploration account of the Irthlingborough workings themselves has been published — unlike some of the smaller Northamptonshire ironstone mines further north around Kettering, where a 2010 Derelict Places report describes entering workings still holding hand-drilled faces, tools and rail-and-brick roof supports, and separately records oxygen down to 17 per cent in an adjacent mine and falling with distance from the entrance.

Very little. The brick arch of the tunnel entrance with its "EV 1915" datestone is recorded on the county Historic Environment Record, along with a circular reservoir to the east and the earthworks of the mineral tramway; the calcining kilns and the quarry faces have gone.

Redevelopment

The quarries and ironworks site north-west of the town has been built over with housing and industrial development, which is why a working of this size leaves so faint a mark on the modern map.

Abandoned workings can be dangerous — unstable ground, uncapped shafts, flooding and bad air are common even where a site looks safe from the surface. This entry describes history and general location only; it is not an access guide.

Recorded claims

Individual factual claims, each attached to the source(s) that support it below. Where sources disagree, both are kept.

• Ebbw Vale Steel, Iron and Coal Company began quarrying ironstone at Irthlingborough in 1915; the mine entrance carries a datestone reading 'EV 1915'. ^1,2
• From 1918 the company drove a large underground mine, worked by pillar-and-stall. ^3,2
• The main tunnel was driven about three-quarters of a mile from the Nene valley at a rising gradient of 1 in 210, assisted by two 13 ft diameter shafts sunk 1,100 ft apart; No. 2 shaft afterwards served as the ventilation shaft. ³
• Near the mine entrance the ironstone lies some 60 to 80 feet beneath the surface. ³
• Employment rose from 55 in June 1916 to 91 by the end of that year; fifteen Cornish miners recruited in June 1917 mostly stayed only about eight weeks. ³
• Around 150,000 tons of ore had been despatched to South Wales by the time the underground mine opened in 1920. ³
• Underground haulage used a 3 ft gauge railway electrified from an overhead wire at 250 volts, with two GEC electric locomotives of 1938 and six by Greenwood and Batley of 1941, rated at 240-260 horsepower. ²
• Richard Thomas and Company bought the mine in 1935 and extended the main tunnel to the Finedon quarries in 1938; Richard Thomas and Baldwins Ltd operated it from 1945. ²
• In 1951 the Ministry of Works assessed the mine for the Central Register of Underground Accommodation and reserved it as possible storage for museum and art gallery exhibits, reporting on its access, ventilation, services and vulnerability to bombing. ¹
• The Coal Authority's three-sheet abandonment plan for Irthlingborough (OM15242) gives an abandonment date of 30 September 1965. (disputed) ⁴
• The Richard Thomas and Baldwins plan of the Northampton Sands ironstone mine at Irthlingborough (KP23319) is catalogued as abandoned in 1966. (disputed) ⁵
• The tunnel entrance was bricked up after closure and the workings are sealed; the quarries and surface works have been built over by housing and industry. ^1,6
• A 2010 forum report on other Northamptonshire ironstone mines, near Kettering, describes accessible workings retaining hand-drilled faces, abandoned tools and rail-and-brick roof supports, and records oxygen at 17 per cent in an adjacent mine, falling further from the entrance. (uncertain) ⁷

Photographs & further reading

This page doesn't try to reproduce everything — these are the best original sources found for this mine.

Sources

1. (primary) Monument record 7197/1/6 — Tunnel Entrance into Ironstone Mines, Irthlingborough — Northamptonshire Historic Environment Record
2. (secondary) Irthlingborough (Ebbw Vale) Iron Mine — AditNow
3. (secondary) Irthlingborough Iron Ore Mine — illustrated text by Alan J. Pack — apack1.co.uk
4. (primary) Mine plan OM15242: Irthlingborough (3 sheets) — British Geological Survey / Mining Remediation Authority mine plans catalogue
5. (primary) Mine plan KP23319: Richard Thomas and Baldwins Ltd, Northampton Sands Ironstone Mine, Irthlingborough — British Geological Survey / Mining Remediation Authority mine plans catalogue
6. (primary) Monument record 7197/1 — Ebbw Vale Iron Ore Works, Irthlingborough — Northamptonshire Historic Environment Record
7. (observational) Northamptonshire ironstone mines (forum report, April 2010) — Derelict Places
8. (secondary) Nene Valley Mines Study Group — Nene Valley Mines Study Group

Record created: 24 August 2026 · Last researched: 24 August 2026