A colleague of mine left the RAF after a full career which included a current enhanced vetting (his, you couldn't get any higher). He applied for a job at an area HQ with the ATC [J Class commission?] for which he had to be security vetted. They would not accept his current vetting, even though it's the same people doing it.
10 month later he got the go-ahead to work. Talk about a gross waste of the taxpayers' money?
CRB checks are also required for those in the health service who may have to have contact with children - doctors, nurses, etc. That is administered by the local Primary Care trust, who hold the records. Now before you employ a nurse in the local surgery, you have to wait for the check to come through - weeks and weeks of waiting involved.
The system is not keeping up with demand, because the resources or funding have not been allocated. Central gov seems content to make up these laws as they go along, without fully considering the consequences. The country is in danger of grinding slowly to a halt under the weight of under-resourced bureaucracy.