Hi Emma
I suggest doing a Subject Access Request to Capquest. This costs £10 and there is a template letter in this site's library. This should provide you will all the information they have for this account from the time they acquired it, including whether they have registered a default with any credit reference agencies.
Normally a debt is statute barred if 6 years have passed since a payment or acknowledgement of the debt has been made. However this 6 year time limit started to run again in you hubby's case from the date that he first acknowledged the debt to Capquest. (Pity you were curious!!

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I also suggest doing a CCA request to Capquest under s77-79 of the Act for a copy of the original executed credit agreement. This costs £1 and there is a template letter in this site's library. They have to supply a true copy of the ORIGINAL agreement within 12 working days or they are in default and cannot enforce the agreement. If they are still in default after a further month then they have committed a criminal offence which carries the penalty of a hefty fine or even inprisonment.
The chances are that after all this time a true copy of the agreement will not be forthcoming.
Regards, Pam