|Yes, I'm aware of that many of the Turbo sessions' bonus tracks were released on the 2001-2002 remasters. I merely mentioned the ones that were listed in the book but haven't been released. A total of 18 songs were recorded in 1985, with six of the discarded songs being named: Red White and Blue, All Fired Up, and Prisoner of your Eyes have been released on the remasters and Heart of a Lion on Metalogy. Hard as Iron and Love You to Death are mentioned as having been originally meant for Turbo, but were re-recorded and put on Ram It Down instead. Fire Burns Below and Thunder Road might originate from the Turbo era as well.|
The same biography also mentioned that Priest recorded some material for the upcoming Screaming for Vengeance at Ibiza in September-October '81, but they eventually rejected those recordings and started from scratch. A 1982 Kerrang! interview with Rob Halford is quoted as "We've recorded seven songs and as usual we'll be aiming for a total of 10. The material is varied: some of the songs are as intricate as Sin After Sin and Stained Class, others are as raw and as primitive as British Steel and there are those that are in the style of Point of Entry...It'll pobably be the heaviest thing we've put out...We go back to the studios at the beginning of the year. How much of those eventually rejected Ibiza sessions made it to the final album is unknown.
There's surely at least one or two unreleased songs from each album's sessions - none have been released from the Sin After Sin sessions (Race WIth the Devil having been recorded at the Stained Class sessions), only the aforementioned track from the Stained Class sessions, nothing from the Killing Machine, British Steel or Point of Entry sessions, only Fight for Your Life (aka demo-Rock Hard Ride Free) from the Screaming for Vengeance sessions, nothing from the Defenders of the Faith sessions (despite taking a very long time to record), but then there's a load of stuff from the Turbo and Ram It Down sessions (apart from the songs I mentioned in my previous post). And finally, Painkiller has a bonus track from it's own sessions, so there might or might not be more. Around before Priest...Live! was released, the band actually thought of releasing a double album, with the other disc consisting of unreleased studio material and the other from live stuff, but they eventually made it into a double live album instead. And, as Maple Syrup correctly noted, Priest recorded three tracks in 1987 with pop producers Stock-Aitken-Waterman (who produced Rick Astley among others), but after the harsh criticism they faced after Turbo, they left the tracks unreleased (as Glenn Tipton said in '88: "we can't afford to release anything that's not Priest right now").
Oh, and the Gull Records remark in my previous post was meant for the Mother Sun song, I originally meant to just edit it in.