Robert Maudsley has been dubbed the most dangerous serial killer in Britain for his horrific crimes and is considered such a risk he will remain isolated in an underground cell until he dies. The murderer , 71, has been in jail for 50 years since being found guilty of garrotting convicted child molester John Farrell, aged 30, in 1974. In January last year, the Mirror reported that the twisted killer had set a new world record for the most days spent in solitary confinement , then standing at 16,