Colwall Old Tunnel is not that unknown, being visible from trains about to enter New Tunnel, but it's history has an unusual twist. Having been replaced as a main line tunnel, it was used as an ammunition store during WW2 and was equipped with a narrow gauge line at that time to facilitate the movement of stores.
This reminds me of one of my favourites, Euroclydon Tunnel in the Forest of Dean (also known as Hawthorns Tunnel), which was very strange for a number of reasons.
Firstly, the original contractors were dismissed for various reasons, one being that the headings were 7 feet off true - later discounted (but see below).
Second, the tunnel was completed, and the line from near Cinderford to Mitcheldean Road fully laid, by the GWR in 1877/8, but for some reason the company decided not to use it - it lay unused until 1917 when it was finally lifted.
Thirdly, although only 638 yards long it was built on a reverse curve, so S-shaped, which may have led to the construction difficulties.
Fourth, like Colwall Old, it was used in WW2 as an ammunition store, laid with a concrete base and a narrow-gauge railway to connect with the standard gauge sidings in the quarry at the southern entrance.
And finally - at about the midway point there is a strange cave, accessed through one of the normal recesses - which suggests that maybe there was a mismatch with the tunnel construction - I can think of no other reason for it being there.
There is a good description of it
here on the website mentioned above, with some excellent photos, far better than any I could manage.
I walked it about 40 years ago. It was quite scary - I was on my own, and access from the northern portal was by climbing through a hole in the wall that had been built across the entrance and jumping down the other side - I wasn't sure if I'd be able to climb out again! But walking was easy on the concrete floor, and the strange cave was intriguing and quite large. I remember the abandoned equipment inside but strangely not the n.g. railway. And, deep joy, the far end opened out into a working quarry; I just tried to look inconspicuous and walked out through the gates.
Here's an amusing line from Harry Paar's
The Great Western Railway in Dean:
Ganger James of Bilson Junction used to get permission to take his trolley through to Mitcheldean Road to convey his daughter's luggage and, so far as is known, this the only beneficial use which was ever made of the line.
Did he not take his daughter as well? Did the poor girl have to walk over the top?
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