You are confusing a contract debt with a CCJ.
Many contact debts (unpaid bills, fines, loans etc) become 'statute barred' six years after the default date, providing certain criteria are met.
- You or anyone else owing the money (if your debt is in joint names) have not made a payment towards the debt during the six year period.
- You or anyone else owing the money have not written to the creditor admitting you owe the debt during the six year period.
If you, or anyone else owing the money, have done either of the above, the six year period 'resets' from that point.
FYI - even if a debt is statute barred, it doesn't mean that the debt no longer exists. In simple terms, it means that a creditor cannot ask a court to enforce it with a CCJ.
A creditor can still ask for the money, by letter, telephone or in person.
Always check your credit file to see if a CCJ has genuinely been granted against you. Collection agencies (especially those who specialise in buying expired/expiring debts for pennies on the pound) will go to great lengths to 'spook' people into acknowledging or paying towards statute barred debts, even when those debts are not legally enforceable.
If a CCJ has been issued, or if action to obtain one has started, the six year barring period no longer applies. However, the creditor would need to reapply to the court for permission to enforce a CCJ more than six years old. They must have a good reason as to why the CCJ hasn't been enforced up to that point, eg you had left the court's jurisdiction, evaded them etc.
This would have been your situation if you had ignored the letter - the CCJ had already been issued, so the creditor would have taken enforcement action against you at the address they found you at, reapplying for permission from the court if/when the six years had passed.
In your case, where you are sure that a valid CCJ exists, the advice should always be to pay it as soon as you're able.