70th anniversary of an aircraft factory hidden in a tube tunnel

After 16 months of preparation during the height of the blitz, a secret aircraft components factory was completed deep underground in North London in what were unfinished tunnels for the Central Line extension. The factory was completed in March 1942, so I have missed the anniversary, but no one else seemed to mark it either, so I am still going to write about it.

The factory was operated by the electronics manufacturer, Plessey and after their Ilford factory was bombed in late 1940, they persuaded the Air Ministry and London Transport to let them use the unfinished tunnels between Leytonstone and Gants Hill as a wartime factory. The conversion of the tunnels into a factory was completed in March 1942 at a cost of £500,000, giving Plessey 300,000 sq.ft. of factory space.

Parts of the factory was actually in use before March 1942 – but the conversion was staggered over time and completed 70 years ago last month. The sort of things being assembled in the factory included wiring sets for Halifax and Lancaster bombers,wireless equipment, field telephones, and Enigma Code-breaking “Bombes” for Bletchley Park. Up to 4,000 people – mainly women – worked in the tunnels for the four years that it was in use.

Workers worked long hours, beginning at 7.30am and often working overtime for no pay. Knowledge that they were doing their bit for the war effort was enough of a compensation for many people. It must have been a very odd environment for people who were more used to working in large well lit ventilated and lit factories to suddenly be plunged into a tunnel with no daylight, limited fresh air and no smoking. The toilets were presumably at the surface, with maybe emergency chemical toilets in the tunnels – which would mirror how some shelters were designed at the time.

Access into the factory was via the three unfinished tube stations at Wanstead, Redbridge and Gant’s Hill – and two more intermediate shafts were installed to let goods and deliveries to be taken down to the submerged factory. Although the stations at Wanstead and Gant’s Hill are quite deep, the one at Redbridge is in a valley and almost comes back up to the surface at that point. In order to pile up some additional protection from bombs, soil from the construction of the deep level shelters in central London was dumped around the station to build up the depth. As the valley was caused by the River Roding, a couple of water tight doors were also installed in the tunnels around there just in case a bomb did manage to hit the location.

Although built in unfinished tube tunnels, it still had its own mini-railway to carry components along the factory – you can see the tracks in the photo above. The railway was supposed to be used just for goods deliveries, but apparently made for a useful service when VIPs visited the site.

It wasn’t just the tunnels though – the stations were used – as shown in this under conversion photo of the platforms at Redbridge station and also there were storage facilities at the surface.

After the war, the factory was removed and the tunnels converted back to their original purpose, an extension for the Central Line, and in 1947 finally opened as such. An article from the London Illustrated News, December 6th 1947 had some details about the factory – although the cut-away drawing massively exaggerated the depth at Redbridge station, which is just two flights of stairs – not a deep escalator.

Today, the three stations are just ordinary tube stations without a single hint left of their war time endeavours. Not even a plaque that I could see.

Although Gant’s Hill platform corridor is rightly famous, the surface building is a decaying slab in the middle of the roundabout.

Gant's Hill

Gant's Hill

Back tracking along the Central Line at surface level, if you know where and what to look for, there is a very distinctive brick tower stuck between two houses on a main road. This is today a ventilation shaft, but was originally constructed as a lift tower mainly to carry goods in and out of the factory, but also offered a short cut to work for those living close to it.

Surface vent shaft

As I was photographing it, one of the neighbours came over and asked me if I worked for London Underground and could I tell them that the front needs to be cleared up. I can see her point!

Surface vent shaft

Those plants looked like Buddleja – which is generally considered to be a weed by railway companies as it has very invasive and hard to remove roots. If TfL were to clear it – maybe they could agree to let the neighbours use the space for pot plants? Topically, considering I am writing about wartime efforts – the plant is very swift at colonising rubble, and was nicknamed ‘the bombsite plant‘ among people of the war-time generation.

Further along the road is Redbridge station – the one with tracks closest to the surface and which was covered over in extra soil. I presume that had it not been used as a WW2 factory, it might have been an open air station as it is today just two flights of stairs down to the platform.

Redbridge

Redbridge

A quick trip on the train over to Wanstead station.

Wanstead

Wanstead

Now to find something which was only cursorily mentioned  in the researches – another ventilation shaft. I knew that two shafts were constructed and that one of them was on Cambridge Park, which is a road between two stations. Some searching on Google satellite view suggested a target, and checking with the Land Registry confirmed that this plot of land is indeed owned by London Underground – along with various sub-surface features.

The octagonal brick tower peering out between two houses.

Surface vent shaft

And visible from a secure and unmarked gate. The sign on the door by the tower warned of a deep shaft within.

Surface vent shaft

That’s all that’s visible today. Which is a pity as I think it would be nice to remember the unusual and vital use this section of the Central Line was put to during the war.

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12 Comments

  1. Janey

    Another great read Ian, always interesting articles :)

  2. James

    All the concrete reinforcement caused some issues during some major delays during roadworks a few years ago. Seems someone forgot about the tunnel’s past.

    Article from local paper
    http://preview.tinyurl.com/threcorder-co-uk

  3. David S

    Redbridge was always intended to be a covered station. The station building was designed by renowned Tube architect, Charles Holden. The platform area itself was built as cut and cover. At the far end of the station carpark is another small building which I was told by some engineers working there when they did the signalling upgrading led to a sort of complex under the carpark. There is also a further tower which is now in the middle of the roundabout.

  4. ian gale

    in the round corridor of gants hill station are sealed metal like doors painted white ,behind them are the secret war factories making spare engine parts for vickers during the war,today people dont see them as a doorway to tunnels under gants hill,one of them is just five feet above the tube roof,another is a 35ft shaft to the sewer in case of severe bombing escaping down the sewer leading to ilford high rd ,some of the books written in the sixties quoted a house which was the exit out of the tunnels,a normal house in the street,700 yards from the station,its quite hard to find now,but can be found …happy trails ian.

  5. A really interesting read Ian. I love anything to do with the war and articles like this keeps my interest fuelled.

  6. Pete T

    Absolutely fascinating article…and follow-on comments – thank you ALL so much!
    I grew up around Gant’s Hill & spent many a happy hour playing / cycling around the many station entrances (incl. SevenWays Parade?) but not even my parents were aware of the underground factory…and my Dad was an Air Raid Warden for some of the war.

    Thanks also to my son (an avid historical architecture buff) who saw your article & passed it on to me – we are all down on the South Coast know…but still have strong links (Essex Cricket Club + the remaining Leyton Orient fan).

  7. Bernard Willis

    I looked up the Wanstead Station page to try to find the date that it was opened. I am writing my Life Story & I used the station on the first day it was opened to return to my barracks in 1947 when doing my National Service. In 1937 my parents, sister and I lived at 71 Cambridge Park. London Transport made a compulsory purchase of the property to build their air shaft. We moved to Nutter Lane where another air shaft was built about 100 yards away in the central reservation of Easter Avenue. I can well remember the stories of the “secret” war factory of Plesseys in the underground tunnel. Thought you might like my first hand knowledge of this. P.S. I now live in Cornwall/

  8. Neil Iosson

    There is a commerative plaque at Wanstead station – in the hall between the platforms where the escalator comes down.

  9. Paul Harrison

    My Mum, Olive, worked down the tunnel during the war. She will be 90 this year.Some years ago she wrote this about her experiece there:
    “Mum, by that time, had got herself a job at Plessey aircraft factory, working in the Underground tunnel in Wanstead. She said “Why don’t you come to Plessey ?”. I didn’t like the idea of machine work, so I went to Ley Street, Ilford and had an interview to do inspection work. So I started going to Wanstead with Mum – and that lasted the duration of the war.
    When we got to Wanstead Station, hoards of people were converging to the entrance. You had to show your pass to the security man. There were two security men. Then in you go, down the escalator – wave to Mr Fossey – he worked in the drawing office on the left hand side. They all wore green eye-shades. Then we clocked in. It was fantastic – we walked past machines three yards long on the left hand side and the other side had a little railway line for taking materials up and down and Nobby Clark – the Big Boss of Plessey- would come riding through. It was a hive of activity. After walking for ten minutes, I was left at a green wire mesh cage which was the inspection office. I was introduced and then trotted round to the drills. To get there you had to duck down and walk through a little tunnel to get onto the other platform (the ‘up line’ and the ‘down line’). I was told what to do. They gave me a rubber stamp, a metal stamp and a rejection pad. They told me all about dockets and drawings. I had to buy my own rule and pencils.
    The air-conditioning and lighting was superb. As soon as I got the idea, I had to go with another person up top to get two white coats. Round about 10a.m. a bell went off and we all got a ten minute break – you grabbed a wooden box and sat with your friends. A man who was disabled came limping down the tunnel with two white enamel pails and a ladle – and that was tea. A woman behind him had a trolley piled high with the most delicious cheese rolls I’ve ever had, and yellow-peril cakes. They looked after the forces and munitions workers when it came to food.
    I started checking seven machines and got on very well. The setter was a nice chap. His name was Frankel – a Jew, I think.
    There were rats down there. The first two rats I saw I thought were kittens. One was ginger, the other one was black. Once I had a rat run over my foot ! I started leaping about, and that caused a laugh.
    I progressed to every line in that tunnel; mills, tapping, baleys, Capstans. I got efficiency money, but in those days we didn’t get paid well, so I went on permanent night work.
    When I worked in the tunnel, one night a chap called Bob Olsen came in and he looked terrible. He was a charge-hand. He was about thirty-five to forty, quite old to me being only twenty. His face was ashen and he was just like a zombie. His house and all his family were bombed outright. He kept working. There was nothing else to do”

  10. Joe kelly

    Hi Ian, very interesting stuff. My father who is 89 this year used to work for Plessey in the tunnel and also in a house on the Eastern Avenue which was used as a lab. In the back garden of the house was one of the access shafts, possibly the one in your photos. He went to work one day to find the house had been bombed. He also has a great story of going to the door and being confronted by a brush salesman who asked “Is your mum in son?”. he said no but the chap wouldn’t take no for an answer. Eventually he went. It struck my father that the chap didn’t think it a little odd that a boy, wearing a lab coat opened the door during the day, was not a school or work? He said many people would walk through the house and out the back into the tunnel every day and nobody said a thing. Also, in the summer, the girls used to come up for lunch and a smoke and sit on the roundabouts at Gants Hill and Redbridge stations and nobody thought it was unusual or asked where they had come from. When there was a raid on, he would walk down the unused, dark parts of the track from Wanstead, under the river Roding to get to work and avoid the bombs. I’ll ask him to check out your site and give his own account.

  11. Diana

    I have been looking for this information for so long. My mother worked under Wanstead station on nights. I have seen nothing since the East London Advertiser did a review many years ago. Thank you so much

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