Some data held about you will not be revealed, mainly the data which identifies other people or which is intelligence information. Or rumour.
"The Data Protection Act means that in certain circumstances the Metropolitan Police Service may decide not to provide you with some personal data. For example, we will not provide personal data if we feel releasing it to you would be likely to prejudice policing purposes, and we may not provide you with information that identifies other individuals"
This level of check involves an additional level of check to those carried out for the Standard CRB check - a check on local police records. Where local police records contain additional information that may be relevant to the post the applicant is being considered for, the Chief Officer of police may release information for inclusion in an Enhanced check. Exceptionally, and in a very small number of circumstances (typically to protect the integrity of current police investigations), additional information may be sent under separate cover to the Countersignatory and should not be revealed to the applicant."