As much as I like this tune, I am guessing that one would need a serious dose of LSD for the lyrics to make any sense. :)
Seems like it has something to do with a possibly drunken UK lager lout getting seasick possibly on a channel ferry. He falls overboard and meets a mermaid.
I think the keyboard player sued to be included for songwriting credits because the organ bots were such an integral part of the song.