King's Cross Thameslink interchange subway

Perhaps some of the tunnel was built as an access or ventilation shaft when the Vic was built?

In some 50 years of reading about LT, I have never seen this mentioned. Of course, to a committed conspiracy theorist, the lack of evidence merely proves the conspiracy....

The official story is that LT wanted to test different methods of building tube tunnels. In 1959, the Government approved construction of one mile of twin tube tunnel between Finsbury Park and S Tottenham, on the alignment approved by Parliament in 1955. The section from Manor House to Tottenham was lined with cast iron, but using a new method of construction. From Manor House to Finsbury Park pre-cast concrete was used for lining, in various thicknesses.

If you believe all the rumours the Vic line has a non public station for HM perhaps thats why it don't go too near the palace. There are however tunnel segments on the Central line with GPO on them, also you have to remember that when any tunnelling is done it normally goes quite close to sensitive locations and that can mean anything.

Speaking of hidden tunnels... I've always wondered what that lit up section to the left as you depart Oxford Circus southbound on the Victoria line, probably a storage facility...

<finds stapled copy of book> Best to remember, that Nigel P wrote his book without the benefit of what we know now. AFAICR the Inglis report is available as a FoI request. At a guess, tunnel segments with 'GPO' on them are spares/cast at the same time as Guardian, Anchor and Kingsway. Perhaps a topic that merits further research, not forgetting the railway under Mount Pleasant.

An interesting and neglected avenue of tunnel construction, I feel. Pre- NATM and with more intruige!

Indeed - are there tunnel segments on the Central with 'GPO' in them? Certainly would be interesting if there were - perhaps the tunnel equivalent of 'spot resleepering'. Where? Liverpool Street or between Chancery Lane and St. Pauls. Kingsway is underneath Chancery Lane, so if any tunnel segments shifted during the construction of the Kingsway extension in 1949 - 51 it would make sense to use the ready supply of segments on hand. Click here and go to the second picture down - the Main Distribution Frame for Kingsway exchange - I think the tunnel segments there look dashed familiar to LT eyes.

Interesting, very interesting! In my many years at LU I heard many stories about all sorts of tunnels and facilities connected to the Underground network.

I have always had an open mind on the subject but over the years as I walked most of the Underground network I think many have turned out to be more myth than substance. I knew about Holborn/Museum tandem at Kingsway because I was a telephone engineer before I joined LT and worked alongside staff who had been on secondment at Kingsway and other such locations. At one time there was direct access to Kingsway from Chancery Lane station just as at one time there was direct access to the Houses of Parliament from Westminster.

Much of the GPO telephone network in London runs in the long defunct tunnels of the Atmospheric Traction Company (Gas and Electricity distribution also uses some of this former lift company's tunnels). These old tunnels were added to before WW2, during WW2 and afterwards, the LU network was used to connect parts of of the GPO network to other wartime facilities via Trafalgar Square and the Bakerloo line to South London. Remember that Churchill and the Railway Executive were at Down st, Anti Aircraft Control at Brompton Road, CEGB at St.Pauls etc. The BBC had cables running on the Central line from Wood Lane and Dollis Hill was an important GPO research facility on war work, also the munitions and aircraft parts factory in the new Central line eastern extension tunnels etc. many facilities were all interlinked throughout London using the largest conduit in London.

I was told that Down Street was quite a place but in the 10 years that I worked there it was quite obvious that it was never any bigger than the originally built station cleverly divided to make the most of the space. The Aldwych branch second tunnel was similarly used divided into offices and dormitories on two levels just like the government tunnels built as civilian shelters and connected to the Northern line in North, South and Central London.

There are massive spaces underground which are part of the LU network, many of which I had the opportunity to explore over the years such as Baker Street, Bond Street, Oxford Circus, Leicester Square, Waterloo, London Bridge, Green Park, Euston etc. Many of these spaces were once lift shafts or station passageways and platforms. These days Oxford Circus uses one of its disused shafts as an underground substation but there are several others, two of which are either side of Argyll Street and of course there was once an underground substation at Embankment which is perhaps one of the largest derelict caverns on the system although it is used to link the Northern, Bakerloo and District lines via other disused passageways and shafts for cabling purposes.

I expect I would be lost at King's Cross now following all the recent works but there was plenty of non-public area there in bygone years, indeed much of the old ticket hall was still extant off the bull ring still decorated in its original green tiling, the area having become ISTR a pump room.
Certainly part of the Thameslink subway was in existence long before it was built, I can recall that it ran from the Northern to the Piccadilly concourse and was privileged to be shown it by the station supervisor in the late 1970s. I believe it may have been the original entrance/exit from the platforms to the old lifts though I don't know. In those days I was not as interested in checking the dates on segments as I later became when I explored places such as Moorgate and Stockwell.

No-one has so far mentioned the stainless steel segments to be found on the Victoria line. In the standard Victoria line running tunnels there are steel and concrete segments but some of the steel segments are of a different pattern being flat rather than chunky and wider than the normal CI rings. In crossover and station tunnels and escalator shafts and passageways normal CI rings in various sizes are used to allow for the various circumference requirements.

Seven Sisters was my 'home' station when I lived in London so I spent a lot of time travelling the Victoria line. It was not until I had to survey it from Walthamstow to Euston that I noticed the different segments although I had always been aware of both concrete and steel segments being used. The careful shaping of the tunnel into cone shapes to improve forced air ventilation was something I had not seen before and the access shafts to the substations seemed much larger than on older lines. I also had the chance to use and explore the emergency detrainment point between Seven sisters and Manor House and have always suspected that this was perhaps where the original Victoria Line tunnel was built from/to Manor House. Of course Manor House is itself an interesting site as it encompasses not only the station but also the substation around the corner which houses the LT Manor House telephone exchange and ventilation shaft and lies directly behind the old bus offices which apparently sit above what was once a single deck tram depot. I went to the offices for my initial recruitment test and eye test way back in 1976 and over the years explored all the other areas except the area beneath the bus offices!

As for an EEC segment mountain I don't know nowadays but back in the 1970s/80s there was certainly one in a compound alongside the Central line at Snaresbrook IIRC and after Walthamstow bus garage closed I believe that segments were also stored there as well.

I also remember the tunnel segment mountains at (?)Snaresbrook too. I believe they were there for many decades, after originally being ordered for one of the cancelled LU extension projects. They were eventually cleared when a housing development was built. I do not know if they were usable by then or if they just got scrapped but it was certainly a very large quantity.

I believe Stockwell depot was on the surface east of the station and line, and accessed by an steeply inclined connection leading from the south running tunnel. From what I remember reading this incline was blocked off by the construction of the southbound Victoria line, although of course the depot had by then long gone.

Just to add to my original post on this, I had a better look at the segments in the KX Thameslink interchange passage yesterday. Those at the top of the stairs from the Victoria line, and for around 10 yards along the passage towards the Piccadilly, are all date stamped 1977. The remaining segments towards the Picc are dated a mixture of 1967 and 1968.

This means that the 1967/8 segments weren't part of the original construction of the Victoria line, but I suspect they may have been some left over from the construction of the Brixton extension and kept at the Snaresbrook store mentioned above.

The 1977 segments are bugging me - I don't think they could have been made for the KXT passage specifically, because that wouldn't have been approved until after then. They also can't relate to the original Jubilee line, because all the tunnel construction work was finished by then and segments would have been made a few years before then. Are they possibly from part of the abortive Fleet/River/Jubilee line proposed extension or the experimental tunnel built around New Cross?