For background, it's best to trawl through the Eastern section first. see here.
For the Western section of the Mail Rail, I've gone graphic crazy, and labelled all the stations, even including an arrow, for those who have no idea about directions. Ladies, I'm looking at you! This would be the slightly longer section and involve more stations.

Western Central Sorting Office

Another quarter of an hour run, and we were greeted by the sounds of tube trains somewhere close, rattling by. When you're underground, it's one of the weirdest things to hear other tunnels somewhere above or to your side being utilised. Makes you realise just how Swiss cheese like subterranean London is. We eventually were made aware of the site below. You can tell you're approaching a station. After plodding along and ducking & diving strip lights, weaving through stalactites, one is met by two tunnels usually, in a slightly larger tunnel section. One of the tunnels is usually smaller and is the loop track, the other is smaller than the tunnel section you're in, but not as small as the loop track, and leads to the station. I assume this has something to do with airflow. Also, the tunnel to the track is uphill going in, and downhill coming out, in order to decelerate or accelerate the train.

A Mail Rail train sits in the station at WCSO, this would be an interesting station, as it's where the ravers broke into. We approached it with caution.

However as there seemed to be no sign of anything too different from other stations, the caution quickly slipped, and we enjoyed the explore. I get the feeling that Mr J Scott was some sort of overall controller of the Mail Rail, as his name was everywhere. On phone lists, manuals and stuck here above a track controller board.

The pipe ninja, getting really tired at this point, takes a rest on a train. Have to say, those t-shirts look really cool!

Wide shot of the platform, relatively undamaged by the ravers. The only signs being beer cans and wine bottles in the stairwell of the fire escape. The main access to the station on the right being bricked up, sealing the station off from the outside world. The office above is disused, and used for various art and exhibitions until a buyer is found.

Western Delivery Office - Rathbone Place

We didn't get far into this station, before we heard quite a lot of activity going on, and way too close for comfort. I took the shot below, and just didn't feel safe, so we both ran to the far end of the platform.

Another quick shot here, and we disappeared off West. It was only on coming back through later on, that we took more pictures. Having completed the route. Apologies if i've given away the ending to this tale!

This station was very different to the other stations, it being built long after the others were. The Wimpole St office wasn't working out due to difficulty getting vehicles in. So a new station was built in the 1960s. The walls are vertical here, and the station more open, with a central set of conveyor belts in the middle of the platforms. Sadly
due to tiredness mainly, I gave up looking for the right light switch, and also due to the fact you could see into the station above through a mesh above the conveyor belts. So lights might give things away. This shot is looking East towards Mount pleasant.

Looking East up the platform, wire mesh boxes sit below some stairs. A chute pops out below the stairs for once waiting mini york trucks. The small bulb like object hanging down from the ceiling on the far right, is a button to activate the starting of the trains to leave the station. There are several along the length of most stations platforms.

Looking West and another chute. Note the time, I had been awake since 8am the previous day, and Kev wasn't far off that either. We were on the way back at this point though, and by midday we were out.

As we left the station, we found another tunnel built below the main Mail Rail tunnel. It was a siding that would join up with the tunnel we were in. This shows the height difference between the main Mail Rail tunnels, and the stations. As mentioned above, the tracks slope upwards/downwards at stations to control train velocity.

Old Western Delivery Office - Wimpole St

After the very modern Rathbone Place, it was into the station it replaced in the 1960s. The station was a gold mine of abandonment. I do love coming across untouched items that have been left alone for decades. Here a rather old looking train parked up just at the entrance.

The fact the station hadn't been officially used for over 50 years showed. Like King Edward building out East, it had it's platforms boarded off. Kev at the far end of the platform taking his 50th or something shot to try to eliminate the glare. I tend to think it adds to the photo! The white patches on the ground are bits of flaking paint from the tunnel structure.

A rather old, maybe even original line guide for the trains coming through.

Old rails collecting rust and flaked paint, next to an engineering marvel from yesteryear, when Britain used to make things. Bitter about the UK's industrial decline, moi? never!

The platforms behind the wooden hoarding.

After some time here, we needed to dip into our precious 250ml of water, and gain a little bit of strength to push on again. This time only a short hop of a few minutes walk.

The Westbound linking tunnel to the station with one track. The stencil on the wall shows W310 (Westbound 310ft) Most sections between the inter-station tunnels, were around 350ft including the station. You can just see the end of this section at the end of the tunnel past Kev.

Trundling along with matchsticks keeping our eyes open, it was the traipse through the tunnels. By now we were so tired we barely spoke during these sections. Conserving energy and quietly letting upstairs go to sleep.

Western Parcel Office - Bird St

It wasn't long before we arrived at our next station, the shortest distance between stations. It looked pretty much identical to the previous station, with flaking paint everywhere and hoarding's dividing off the platforms from the tracks.

The steel walls of the tube and paint that's flaked off due to neglect.

Like the previous station, the areas between the tracks were little timewarps. This little booth had a sign in (which you probably can't make out) saying Klaxon. I've no idea what the device below it is. Just to the left of this booth appeared to be a fire escape to the surface. We both eyed it up with keen interest, however as I glanced through the mesh glass, I could see the tell-tale signs of an alarm being present. White wires leading to a small plastic box on the door.

Connecting passage between platforms. Just up the platform one can see an alcove with a brief glimpse at the bricks that block it off from the building above.

More signs of a once proud and flourishing British industry, killed off just because we were uncompetitive in a globalised world. The tunnel next to it heads East. However we were heading West, and the final leg of discovery. Also a station we knew might have a way out.

Paddington Station

The longest of all connections between stations was the last one. Just over a mile. It took 20 minutes stumbling through. I managed to hit a strip light or two coming through, the tiredness making it difficult to see and concentrate.The station was looking in pretty good nick, and like most of the other more recently closed stations, still had chutes for the mail to come out on the platforms.

Health and safety always an issue in non-commercial organisations. Lots of special notices I'd like to have read if my eyes weren't blurry.

Yellow seems to be the colour of choice for service trains everywhere, and no different down here. This battery train was parked up here. One of them being charged.

A worker train, with seats inside the yellow gauzed carriage. This place was really like some seaside mini railway on acid. I'd love to bring one of the freaky rail enthusiasts that operate mini-railways here for them to go nutso. In fact, scrub that, I'd like to know how they operate and go for a whizz around myself.

Unfortunately the best I would get was this little chap. However we were both so tired we just couldn't be arsed.

Below the tracks things were a bit more interesting than previous stations. This being a first aid area. The wipe board on the left wall is full of messages saying goodbye, as the Mail Rail was closing.

In the room next to the first aid post, were racks of switches and a controller board for the station.

Controller board shows the loop at the end, and a siding tunnel for taking trains out of service.

Side profile shot of the switchcraft goodness.

The number that says it all, 14, 330ft. This was the last stencil before Paddington station. It's not the overall length, but indicates the length of the tunnel between stations. It's also a useful indicator if you're walking to the station in tunnels, and wonder as we did "how much further?!" Well, 11,160 would be WPO, 8620 being WCSO and so on until 0 at the EDO in Wh!techapel.

It was amazing to have got in, it was brilliant to have seen a small bit of it, it was mind-blowing to have walked the entire length. The whole thing was just kinda bizarre, the fact this all existed to shift mail around on tiny rails through half size tunnels. Having seen the infrastructure of the tube up close, it was an interesting comparison. But it's just the diddy size of the trains compared to full size equivalents on the main tube in London.

I'd have thought a canny investor would have taken interest in a mini-subway system under London, and the possibilities to rake in cash from willing tourists. The world's best ghost train, with actors leaping out of the infrastructure at unsuspecting customers. Scalextric style races maybe. The possibilities are endless.

As for us, we looked up the track going East, and shuddered. We ploughed deep, and rushed back up the tunnel with a jolly loud roar, the fire we needed to get us all the way back. However we opted not to do this, and sneak out of an exfiltration point we'd spotted. It was good to be back in the fresh air, good to be away from the risk of arrest, and good to be near a Sainsbury's Local to stock up on fruit juice, oatmeal cookies and a pork pie. Nom Nom! What was not so good was to find a parking ticket on my bike. I'd parked somewhere i'd only expected to be an hour, and at midday as it now was, I had been busted by a jobsworth traffic warden git. Riding across London home, I almost fell asleep numerous times, and once remember being honked awake at Knightsbridge.

As those who've done it before will attest, it's kind of depressing that you've done it, as there's very little else that can match it. A bit like Dawn French's first chocolate bar fix, constantly searching for that first high all over again.

Cheers to Kev, awesome explore companion.

A video from this trip can be seen here.