EACH underground station has a mural reflecting the history of the area, such as William Morris at Walthamstow, but there are many more stories lying beneath the network.

The underground railway network has evolved for more than a century into what how we know it today – with each line and station having its own idiosyncrasies.

Revolutionary industrial developments have been made over the years, from steam trains to automatic trains, and stations and tunnels have at times been adapted for more unusual uses.

Parts of the Central Line serving Redbridge and Epping date back to the late 1800s as part of the East Counties Railway branch to Loughton.

The line was transferred to London Transport in 1947 as part of the extension of the Central Line services and coinciding with the electrification of the trains.

But the extension of the line was delayed by the Second World War and during that period, two-and-a-half miles of twin tunnel between Leytonstone and Newbury Park were converted into a Plessey Co Ltd artillery factory as part of the war effort.

Lindsey Collier, project director and creator of the Lee Valley Experience museum in Walthamstow, which tells the story of Lea Valley’s industrial past, said: “It was the longest underground factory in the world.

“There were 2,000 mostly female workers and it operated for 24 hours a day. It was like a little city with secret entrances and a miniature battery-powered train to transport materials.

"It became the most successful underground factory in the country.”

The Victoria Line's origins can be traced back to the Second World War, but it finally opened in stages following between 1968 and 1971.

It was the first deep-level Underground line to be built across central London since the early 1900s and made history by becoming the world's first automatic rail way with the drivers operating the trains by buttons.

Mr Collier said: “The Victoria Line was called “the driverless train”. People were nervous about using it because they thought it didn't have a driver.”

Walthamstow historical society chairman and archaeologist Neil Houghton said: “I think people are interested in the history of the London Underground because so many people use it.

“It was originally run by private companies serving short distances and was never designed to be a network, which is why it can be frustrating.

"But people realise there is a lot more underground than they realise and are fascinated by it."

Mr Collier added: “Waltham Forest is the home of London transport because it started here.

"There is a great history of rail ways just in this little area and these are stories that people should know about before they are lost forever.”

At the Walthamstow Historical Society's meeting on Thursday, September 10, historian Peter Lawrence is giving a talk called 'Underground London', uncovering the mysteries of hidden London including, air raid shelters, sewers and the Underground system.

It is in the main hall in Greenleaf Road Baptist Church, Greenleaf Road, Walthamstow, from 7.30pm.