The current child protection system is still not working effectively, an expert has said.
The introduction of a national computer network has been delayed
Mark Williams-Thomas said a national computer network will not be working fully until 2010, and people can still get around criminal record checks.
His comments come on the fifth anniversary of the abduction of Holly Wells and Jessica Chapman in Soham.
The Home Office said the computer system could bring benefits by 2009 and criminal checks are "highly accurate".
Mr Williams-Thomas, a former police detective who runs a child protection consultancy, has spent 15 years in the field, including working on the Sarah Payne and Jonathan King inquiries.
He said the computer network allowing material to be shared between police forces is running three years late.
The development was one of the recommendations of the Bichard Inquiry, set up to investigate how Ian Huntley secured a job as a school caretaker despite a string of sex allegations against him.
He murdered 10-year-olds Holly and Jessica while working at Soham Village College in Cambridgeshire.
Mr Williams-Thomas said people dodge criminal record checks by changing their name.
Some sporting bodies are ill-equipped to deal with the information they are given anyway, he added.
Mr Williams-Thomas said such flaws are allowing unsuitable people to work with children.
A Home Office spokesman said: "We are not complacent and we remain committed to delivering a comprehensive national police information sharing capability, the Police National Database.
"We anticipate deployment by 2010, with potential for some early benefits to be realised by 2009."
The Home Office said information released from Criminal Records Bureau checks was 99.97% accurate.
Sport England said among other measures it offers specialised training to those dealing with criminal checks.