The ATC used to do all its own security checks through the PSS, following filling in duplicate a form 177 ident. This was happening in the 70s. I know of at least one person who was told told to go and never return to the unit on instructions from PSS. The current system is a total shambles. I work for the NHS and enhanced CRB checks for urgently required staff takes weeks if not months. I suppose it saves maney, but it does p**s off applicants, who lay the blame at our door.