Report - - Where's the Excelsior Tunnel, Cornwall? - March 2011 | Underground Sites | 28DaysLater.co.uk
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Report - Where's the Excelsior Tunnel, Cornwall? - March 2011


Regular User
This is one I’d kept clear of for a while due to its being involved in underground atomic bomb testing, which I now realise was from a misreading of the SubBrit report on http://www.subbrit.org.uk/sb-sites/sites/e/excelsior_tunnel/index.shtml (by the way take a look at picture 3 on that page – is that Spiderman walking to the back of that VW van?)

In fact what they were doing was checking to see whether the Russkies could sign up to a test ban treaty and then cheat by masking the tell-tale seismic signature of an underground atomic bomb explosion (well yeah and probably also checking whether the Allies could too)

They used an abandoned tin, copper and wolfram mine on a hillside at the east end of Cornwall, and in 1959 test fired conventional (I hope) explosives there and did find they could blur the seismic waves created. Further tests carried out elsewhere verified this with the nett result that the test ban treaty failed to get off the ground, and Russian and Cuba invaded the US (http://www.imdb.com/title/tt0087985/ )

Recent pictures on here by some glowing members of 28DL made me decide it was time for a visit. Finding the tunnel is another however another matter – it’s a bit like one of those Where’s Spot? books


Is it in here?


No, bit tricky even for a 28DL SBS mission


Is it in here?


No, bit bloody short if it is


Is it in here? ... wait a minute there's no bloody entrance :confused


Ah yes, this looks more like it :thumb


Past a waterfall ...


and more falling water


a ventilation duct entrance - looks a bit drier in there


roof fall?

By the way, anyone know what that blind passage in picture 5 would have been for?



28DL Full Member
28DL Full Member
No nuclear material was detonated, if you read the Sub Brit article it gives a better analyis of "Operation Orpheus" and its outcomes.


(BTW: this was after my Owd Boy had left AWRE as he was involved in the Malden and Christmas island tests, yes he's still going at 87! - he did go back to Malden Island a few years back to look for the historic remains the he saw 1st time round!)

Garou Garou

28DL Regular User
Regular User
The spherical Chambers were made for testing conventional explosives to characterise the reduction in shock wave compared to solid rock.
I think I saw a reference to them still being there, and they would be cool to get into.

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