St. Mary's was completed in 1884, and used for the District and East London lines. It was too small though, and located on a hefty curve. This and the moving of another station nearby closer to St. M's was it's death sentence. It closed in April 1938. Full wiki info here.
This station had been a bugbear for a long time. Kev had done it on Xmas day along with a large number of other stations, but my absence from the xmas table in the West Midlands would cause a family drama, so I couldn't go. So for endless weeks I turned up to carefully peek at the entrance only to see a blur of orange wandering about. A fortnight previously I had got down to the tracks, only to see two chaps working away on a junction a few metres away. Carefully tip-toeing off to get out. I turned up again to have a look when i was tipped off by Speed that it looked quiet around there. I checked a nearby station, and saw 2 orange overalls on the platform, but a second check after a lap of the block saw they were no longer about. I then found the access point gate had been changed with a menacing whirl of spikes looking to shred my finest Primark/Oxfam attire. So a minute longer than previously, I was in. And crept toward the tracks. constantly looking around, as i was by myself for the first time on a tube station hunt. Normally a partner or two would help on looking for danger. The coast looked clear, and i nervously peered around the corner to see a distinct lack of orange. A last check of the nearby station, and I was off. The annoying crunch of gravel around the tracks hard to avoid as i nervously slow jogged up the tracks and into the cut and cover tunnel. I was surprised to see another tunnel here, as i'd not heard about it. It ran from the cut and cover back towards the nearby station.
It wasn't more than a minute, and I came across a path leading up the left hand side, and I relished the opportunity to get away from the tracks. I was sure they were off, but one never knows. You can see the grey/white path just above the tracks in this photo. It's taken from the right hand side of the station, that has no access to the street above. On the top right, you can see the latticework of the bridge that once crossed the tracks.

Back on the tracks, this was a shot of the latticed footbridge from below, and the tracks leading out to eventually the nearby station.

A style was crossed and I was in the remains of the main station. The majority of which was closed off and used as what I suspect to be a sub-station of some kind. The door on the left in the photo below leads to the street level/evacuation route. The remains of the stairs up to the footbridge can be see in the centre of the photo. The photo was taken on top of what I'm guessing is the substation structure.

The remains of the staircase, still just about useable.

Tracks on the left heading East out of the cut 'n cover, the door on the right the evacuation route door.

On the roof of the substation structure, the remains of the stairs and the lattice footbridge route at it's clearest.

During World War II, this station was used as an air raid shelter, the station having been closed in 1938, the tracks were bricked off from the sub-level station area. The vent being a remnant of that period.

A wide shot of the air raid shelter area, this is where people sat and to some extent lived during air raids. Until October 1940 that is, when the station took a direct hit.

On the other side, or North side of the station, the tracks were blocked off by countless black dust encrusted cables. The green lens flare that's common when trying to take photos of the tracks.

A possibly early tag from Mr. Tox, before he resorted to a mere scribble. On the basis of this attempt, one can see why!

remnants of a building similar to the air raid shelter on the other side of the tracks. Lack of seats on this side suggest it may not have been used as an air raid structure.

Stairs leading up to the lattice footbridge, and hence other side of the station

Back on the Southern side of the station, and just through the evacuation door pointed out earlier, remnants of the original station can be see, rebuilt after the WWII bomb.

From the evacuation door a slope leads up to some steps, and then a door to the street. Looking from the base of the steps to the street down to the evacuation door.

The station emergency board in case of erm, emergency. The door to the street is alarmed, and a phone call to the line controller is required to exit without drama. I opted to exit the way I'd come.