A revenue judgement may last forever and it could add up to six or seven times the original sum because of the rollover interest. I do hope that the judgement has expired otherwise it's going to be costly on you. It is really a question for a professional.
I am not a solicitor but i think some judgments are no longer enforceable after 12 years. However the problem is how you can get it removed. as previous poster said it is a matter for the legal people
I think the statute of limitations on this is 12 years but if it's secured against a property it may be difficult to get it 'off' the property. I have no idea how one would go about this.