Just under 100 years ago, an extension of the Northern Line running under the Thames opened to the public, but 26 years later it would be hit by a German bomb and flooded. It is still sealed off to this day.

The short length of tunnel ran from Charing Cross down to Embankment and back up again via a loop under the Thames. Although I said most of the tunnel is still sealed off following that attack, a small part of it is still accessible, and in fact, used as a convenient storage location by London Underground.

It also contains stalactites!

A couple of years ago, I wrote in depth about that tunnel and the German air raid that flooded it. Subsequent to that I was sent some photos by someone who had permission to go inside the accessible bit of the tunnel, so this is a timely follow up to that earlier article — as today is the 73rd anniversary of that German bombing raid.

All the photos are copyrighted to the photographer, and that person kindly gave me permission to publish them here.

To provide a bit of context, here is a map of the Northern Line loop tunnel that opened in 1914, but was abandoned in 1926 when the Northern Line was extended down to Kennington, where it ended, appropriately enough, in another loop.

The orange tunnels are today’s Northern Line, and the green is the bit of the loop that is still accessible to tube staff.

Needless to say, there is no public access, and having been sent a photo of the entrance from the outside, it is not in a location you could get to particularly easily. I am not putting that photo on here – sorry!

But here is the inside of the tunnel.

A bit further down the tunnel — notice the curious break in the tunnel lining halfway down the photo and how it widens slightly for a few tunnel rings width. No idea why.

A bricked up side tunnel – not sure of its origins, but there is a small side tunnel on the map which could be what this was. Possibly left over from the earlier construction as it appears to be too small for public use. It might have been later reused for ventilation?

Towards the concrete bulkhead that marks the end of the tunnel

The end of the tunnel — beyond that concrete wall is/was an access shaft for ventilation, and just past that is the second bulkhead wall that fortunately had been installed and stopped the Thames flooding into the rest of the Northern Line.

Some day, someone will have to open that bulkhead door and go into inspect the state of the tunnel. What a wonderful experience to be in a tunnel that no one has been in for over 70 years, and to touch the concrete filled sandbags that are presumably still there – holding back the Thames ever since they were hurriedly put in place in September 1940.

Now go and read about the bombing of the Embankment Loop.