Excerpt from link:
In April 2005, Pink Floyd drummer Nick Mason stated that the Publius Enigma did exist, and that it had been instigated by the record company, rather than the band:
"That was a ploy done by EMI. They had a man working for them who adored puzzles. ... He was working for EMI and suggested that a puzzle be created that could be followed on the Web. The prize was never given out. To this day it remains unsolved."