If you were to wait for a southbound Northern line train at Bank tube station you might have noticed that a strange door has appeared on the wrong side of the railway tracks.

Seemingly hidden behind the metal rings that have very visibly been recently removed.

Looking totally out of place on the wrong side of the tracks you might not unreasonably wonder why its there, has it always been there, where does it go.

The door is in fact brand new, so why has the London Underground put a double-door on the wrong side of the tracks — after all no one can use it.

It’s all to do with the massive Bank station upgrade project which is seeing an entirely new tunnel dug right next to the current one, a new travolator added and lots more escalators.

As part of the upgrade, the existing southbound rail tunnel will have the railway filled in, and turned into a passenger corridor, with a link to the new southbound tunnels — which just happens to be on the other side of that door.

As they get closer to opening the new tunnels up, they are in various locations cutting into the existing station to create the new links, which you will be able to see in a number of locations along the Northern line and DLR.

This new door now leads to a corridor to the new southbound platform, and during construction works, they are required to put in place a fire door between the live railway and the new construction site.

Hence, the odd sight of a door in a wall where there reasonably shouldn’t be one.

In a couple of years, that door will vanish and an entirely new Northern line platform will open on the other side.

To see more from the Bank station upgrade, click here.