http://www.dailymail.co.uk/news/article-2031013/Notorious-paedophile-jailed-238-years-abusing-children-free-mingle-children-car-boot-sale.html

Just seen this article, about paedophile Joseph McColgan, 69 being spotted at a car boot sale-even after being jailed for 238 years for beating and raping his own children. 
I don't understand why these people are allowed to be freed? Granted, people get released for good behaviour from jail- but how does that compare to people who are jailed for minor offences?
Would you be happy seeing this man walk around your local car boot sale after the offences he had been convicted of? 
This definitely has shocked a lot of people into understanding how people convicted of these offences can walk our streets freely.