As a father of two daughters I cannot see that CRB checks do any good at all. No one can tell me whether they have prevented a single offence, and it seems quite feasible that anyone who wanted could circumvent the regulations. I have several times been allowed to assist Guides events on the basis that 'We can do the checks later.'
CRB checks cost business and individuals inordinate amounts. The system is wasteful and inefficient (as well as ineffective).
They are a strong disincentive to volunteers who might otherwise give their time to helping children.