Ancient Aviator, your point about Japanese Naval Aviation being Carrier based is well made, but it was essentially an offensive weapon system. Had they developed long range maritime aircraft similar to those of the RAF and USN they could have better defended their merchant shipping against the focussed USN Pacific submarine campaign on them. Perhaps another feature of the post Pearl Harbour hubris of which you speak?
Danny, we did indeed cross. According to the article, the excavation of the tunnels provided for earthworks that could have acted as foundations for the launch ramps of which you speak, and which were aimed towards both Weymouth and Plymouth. It also claims that the tunnel layouts matched those built on the mainland for V1 sites. What seems arguable though are that the hardened storage chambers therein were for chemical warheads rather than conventional ones.
As Alderney was under SS rather than Luftwaffe control (whose V1's they were), it is possible that this was a one off. Though the Nazis produced both Tabun and Sarin in quantity in the war, neither were used operationally
AFAIK. Hitler himself had been gassed in WWI and was notoriously unwilling to invite reprisal in kind if he utilised either offensively. Perhaps the Alderney project was abandoned for that reason, if it was indeed intended for such use?