The singer, 50, was on holiday in Gran Canaria a few years ago and not sleeping very well. After one particularly bad night, he had the idea for the soul opera in his head.
Paul recalled: "It wasn't fully formed, but I do remember thinking it would be a really good idea to have songs about the seven deadly sins, then to create an eighth.
"In my dream, all the other seven - lust, gluttony, greed, sloth, wrath, envy and pride - were talking about something, which I call the whispering of the eighth.
"I knew it was a whisper or a rumour, so that's when I decided the new eighth sin would be gossip. I think it's about time they were updated anyway, and some of them are so similar, like greed and gluttony."
The former Housemartin insisted he's not worried if people understand the opera, which is written in the style of a pulp fiction novel.
"Obviously I want people to get The 8th, but I've spent my career writing lyrics that I think are pretty simple, and there's always someone who doesn't understand them," he said.
"I think I've arrived at a stage in my life where I can think 'I don't care'. Not about people, I always care about people, but the idea that someone isn't going to understand what I'm on about. If they don't get it, they don't get it."
He added: "Also, I'm not on the radio, I don't sell any records, so if it isn't the time to do what I want, I don't know when is."