Visited with my old school friend @Hiddenscotsman. This was his first taster of the underground, so glad you enjoyed it mate! 
Been meaning to check this one out for years, but having lived in the south of England for nearly 7 years I was pretty spoiled for what was available down there, so it was never a priority on a trip back home. After 4/5 months living back north of the wall I was craving an underground explore so we decided on a whim to make the journey after a successful visit elsewhere. As is traditional when we go out anywhere, the longest and most awkward route was chosen. Rather than a casual stroll from the car, we opted to scramble down from the top of the hill after I'd ripped my trousers on the fence, realising there was a 12+ft drop at the bottom we wandered off away from our access point to find a way down. Going as far as we could, we had no choice but to shimmy down a tree. All of this in the pissing rain! Plus we had ended up in the wrong fucking hole in the ground to start with!
(A couple of phone pics from the fail lol)
Pretty sure it's this way...
Yeah... we prob should NOT be in here when it is raining so badly!
Oops!
Anyway, some history yoinked from @elhomer12's report:
This Air Raid Shelter in Port Glasgow was built for the workers of the nearby Gourock Ropeworks, and was the largest privately owned shelter within the UK at the time. It is believed to have been built before the outbreak of WW2 by a group of Polish workers... apparently taking them 6 months to complete.
We eventually got there, and prepared ourselves to get wet feet. I'd heard that the water was currently 13 inches deep inside. My wad0rz got dumped in Portsdown Hill Navy Fuel depot after @Grom and I went, not a chance in hell that oil was coming off, and I have never replaced them. I was hoping the wellies I had in the car would be enough. I was very happy that the water level had dropped and it was just a bit muddy! After a quick smoke we made our way inside...
Needless to say, we chose the 5 min casual stroll back to the car.
Thanks for looking!

Been meaning to check this one out for years, but having lived in the south of England for nearly 7 years I was pretty spoiled for what was available down there, so it was never a priority on a trip back home. After 4/5 months living back north of the wall I was craving an underground explore so we decided on a whim to make the journey after a successful visit elsewhere. As is traditional when we go out anywhere, the longest and most awkward route was chosen. Rather than a casual stroll from the car, we opted to scramble down from the top of the hill after I'd ripped my trousers on the fence, realising there was a 12+ft drop at the bottom we wandered off away from our access point to find a way down. Going as far as we could, we had no choice but to shimmy down a tree. All of this in the pissing rain! Plus we had ended up in the wrong fucking hole in the ground to start with!

(A couple of phone pics from the fail lol)
Pretty sure it's this way...
Yeah... we prob should NOT be in here when it is raining so badly!
Oops!

Anyway, some history yoinked from @elhomer12's report:
This Air Raid Shelter in Port Glasgow was built for the workers of the nearby Gourock Ropeworks, and was the largest privately owned shelter within the UK at the time. It is believed to have been built before the outbreak of WW2 by a group of Polish workers... apparently taking them 6 months to complete.
We eventually got there, and prepared ourselves to get wet feet. I'd heard that the water was currently 13 inches deep inside. My wad0rz got dumped in Portsdown Hill Navy Fuel depot after @Grom and I went, not a chance in hell that oil was coming off, and I have never replaced them. I was hoping the wellies I had in the car would be enough. I was very happy that the water level had dropped and it was just a bit muddy! After a quick smoke we made our way inside...
Needless to say, we chose the 5 min casual stroll back to the car.
Thanks for looking!