Spinner reports that before his death in 1986, Thin Lizzy bassist/frontman and main writer Phil Lynott gave an unidentified caretaker 150 tapes of unreleased music. In 2012, some of the nearly 700 tracks included in the archive will see the light of day – Universal Music has acquired the tapes and the company is prepping a new Thin Lizzy box set which is due out later in 2012.

“This is an absolutely stunning find,” project manager Steve Hammonds told the Irish Independent. The collection will feature outtakes and alternate versions of Lizzy hits, as well as “material which was recorded but never released at the time,” Hammonds added. The recordings span from 1971 to 1981 and total approximately 150 hours.

The group’s surviving members – Scott Gorham, Brian Robertson, Brian Downey, Eric Bell and others – are reportedly helping with the mammoth project. 2012 marks the 26th anniversary of Lynott’s passing, but Hammonds insists this box set is no vulgar cash-in.

“Phil Lynott passed the material on to a third party for safekeeping,” he said. “They held on to it for decades because they were waiting for the right people to come along. They really didn’t trust anyone enough to release it properly,” he added. “No money has changed hands, this person is a Thin Lizzy fan.”