However some companies can ask you to sign to allow them to conduct a credit reference on you, and from the ones we do at my Company they can be very through and will show up "bad debt" or attempts to get credit, as well as accounts/debts that are being well managed.
We can do fraud database check on you as well, and a police bureau check to see if youv'e been in trouble with the law.
If an employer wants to be very through (ie security cleared) they may ask for 10 years of referencing with any periods of unemployment verified by solicitors, proof on bank statements (that you were not working) etc