Just a little clarification or two
A CRB Check and VBS are not the same thing and are run by two different organisations. CRB and Enhanced CRB checks pre-date VBS by quite some time and are required for each and every organisation that a person may work or volunteer for that may have contact with children or vulnerable adults. My 84 year old mother has one that will need to be renewed this year so that she can continue to volunteer with Age UK, and prior to VBS this registration needed to be renewed every year costing charities and employers a fair amount of money and providing Capita with a hefty revenue stream.
VBS registers the enhanced check, and then monitors the person against incoming information. It also shares the registration across organisations, so you only need to apply once, ever, for clearance and you are then monitored. If the system detects a match it is passed to the IBB for a decision. The IBB will then make a decision about the individuals suitability to work with vulnerable people, if it bars you, it does not mean you are a paedophile, it means you are not trustworthy in that area, so for example a petty thief might be barred from working with the elderly and children because they might steal from them.
The enhanced CRB check is, by the way, also carried out and paid for by many employers, and is mandatory, as I understand it, as a part of the Security Clearance process, which is not included within VBS.
The bit of VBS I find iniquitous is that once you are monitored, you are always monitored and you cannot de-register without the consent of the secretary of state. The rationale behind that, is that, if you are convicted of a notifiable offence all your prior employers can be informed to see if you have offended there as well, basically because, in the case of paedophiles, the offending behaviours will go back a long way.
CRB and VBS are now up for merger and renewal, and it's rumoured that ACPO wanted to merge it with NPIA, so the results of the review are likely to be interesting.