The London Underground line that was abandoned halfway through building

A failed Tube project can be spotted on the London Underground map - the station Mill Hill East. This Northern line stop is situated on its own branch, diverging just north of Finchley Central.

Originally, it was part of a proposed extension to the Northern line that would have extended to Edgware and then further into Hertfordshire, incorporating three entirely new stations. The project progressed beyond the planning stage with parts of it constructed before it was abruptly halted, leaving nothing but half-built structures protruding from the landscape of North West London. This extension was part of the Northern Heights Plans which proposed a significant expansion to the upper reaches of the Northern line. The branch was intended to extend from Mill Hill East along one of the branches of the Great Northern Railway through Mill Hill (The Hale) to Edgware. If you take a look at Google Maps, you can see that the line continues from there towards Edgware.

From Edgware, it was planned to continue along a brand new track to three new stations, Brockley Hill, Elstree South and Bushey Heath. The extension was announced in 1935, and construction began shortly afterwards.

However, history had other plans. The 1930s were not a period of great economic or political stability, and with the onset of World War II, plans for Tube extensions into Hertfordshire were understandably put on hold.

There simply wasn't the funding to complete the project during the war, and post-war Green Belt legislation made the extension impractical.

The original purpose of the line was to serve new commuter towns, but these couldn't be built due to Green Belt restrictions. Evidence of the partially completed plan can still be seen across the area today.

At Edgware Station, the line continues into a tunnel where it would have extended. Further along, remnants of bridges intended to cross major roads can be found.

Even an unfinished station is visible. At Cannons Corner roundabout, the initial steps towards creating Brockley Hill Station are visible. The Edgware branch from Mill Hill East was closed in 1964, with only the already electrified section of Mill Hill East remaining.