His growing belief that at least one in 50 inmates is probably not guilty of the crimes began after Stefan Kiszko was freed in 1992 after 16 years in jail for the murder of schoolgirl Lesley Molseed.
Kiszko, who died a year after release, was an inmate at Grendon Underwood jail in Buckinghamshire while Mr Wilson was a governor there.
He was just one of many long-term inmates destined to stay in prison because they refused to admit their guilt and "address their offending behaviour" - a prerequisite for being granted parole.
"Of course he refused - it was absurd," Mr Wilson said.
Mr Wilson, now an academic at the University of Central England, used a technique called "triangulation" to came up with the conclusion that 2 per cent of the country's 65,000 inmates were innocent.Reuse content