Straw inadvertently confirms: it's childporn offences that Venables is being accused of

Justice Secretary Jack Straw inadvertently seemed to confirm (on TODAY just now, around 8.15) that the reason Venables has been recalled to prison IS for child porn offences. In answer to a question from Humphreys about whether he might say more later today about what offences were involved, Straw remarked that as the news had been getting out, the situation was changed. He then realised his mistake and refused to comment further; but this 'non-denial' appears fairly clear. It would now immensely surprise me if it turns out that the offences are not indeed child porn offences.

Which really would underlie the appalling irony of this sad individual's ruined life. A child kills a younger child horrifically, in the public eye (that famous CCTV image). 17 years later, he is apparently engaged in sexual offences - involving images of children. Tragic, for all concerned.
Straw's tacit admission is 10 minutes in:
http://news.bbc.co.uk/today/hi/today/newsid_8555000/8555083.stm