If you went through the 2 sets of holes in the brickwork - one normal sized made up of engineering bricks and one very tight one near the drinking water tag, you would have come out in the courtyard of Melville Court and you would have been able to peek through the airbricks. Melville Court was previously Melville Barracks but had the 1960's tower blocks built on it.Thanks for the link pal
I think the MoD are being disingenuous in saying that they never owned it - sounds like a lazy way of saying "we no longer own Kitchener Barracks, so now nothing to do with us". It does seem that these Royal Marine Deep Shelters were kitted out more for civvy use with the litter bins and womens toilets.
If you walk along Dock Road towards the Main Gate of the Dockyard, you see some steps going down to some bricked off archways and we were wondering whether this was a civilian air raid shelter.