Perfect: In the last year you have no mortgage arrears, CCJs or defaults. Your credit score is high.
Fair: You may have an unsatisfied CCJ and an unsatisfied Default in the last 12 months and some missed unsecured payments. You may have a mortgage arrear in the past 12 months but you are up to date on the last 3 months.
Poor: Numerous small CCJs below £300 and satisfied CCJs below £3000. You also may have 1 large CCJ/Mortgage arrear in the last 12 months.
Very Poor: You may have serious mortgage arrears, CCJs and Defaults. You may have more severe adverse including IVA's/Debt Management plans and bankruptcies.