The novice is classed as a beginner who carries out a murder for the first time, while a dilettante is slightly older and unlikely to have a criminal background. The journeyman is experienced and reliable.
The master hitman is least likely to be caught and probably has a military or paramilitary background. The main reason master hitmen evade justice is because they travel to an area to which they have no ties to carry out the hit. As a result, they leave behind a minimum of local intelligence.
Professor Wilson classed McPhie's murderer as a master hitman. He said: "Hitmen are familiar figures in films and video games, carrying out hits in underworld bars or from the roof tops with expensive sniper rifles.
"With the exception of McPhie, the reality could not be more different. It's quite clear that McPhie's killing was carried out by a master hitman.
"However, the majority of people we analysed were not like that at all and were caught as a result of local intelligence.
"British hitmen are more likely to murder their victim while they walk the dog or go shopping in suburban neighbourhoods.
"The reality of British hitmen is in contrast to the fiction and we hope these profiles will help the police to identify patterns and behavioural traits common to contract killers in Britain."
Their research will be published in the Howard Journal of Criminal Justice, which is used by academics who examine the criminal justice process.