A406/Secret war factory

I heard something really interesting on the radio today and partly related to my project.Apparently during the second world war.Plessey who were a big employer in the UK and had a huge factory in Ilford,very close to where the A406 runs today.It was bomb damaged early on in the war and because it was important to the war effort was granted leave to create a factory deep underground in the tunnels that were dug as an extension for the Central line on the London Underground train network,the extension was postponed until the end of the war.

The factory used 3/4 mile of tunnel and the interesting part is that the entrances to the factory were what were to be the underground stations at Gants Hill,Redbridge and Wanstead.There was also several lift and ventilation shafts built along the route,all of which exist to this day.When the A406 flyover was built after the war and Plessey had moved out of the tunnels to make way for the planned extension they tried to knock them down but being tied to a short building schedule and the shafts being made of reinforced concrete they were built around and incorporated into the construction. I’m going to research further,I think it could be interesting and reinforces the historical arguments for keeping essential war work out of the centre of cities,much like the gunpowder mills in Waltham Abbey.