I've got to the bottom of this. The CSA did an assessment in 1996 and it was questioned because the travel allowance to his (then) employment was wrong. He challenged it unsuccessfully with the CSA but he stopped work because he didn't have enough money to pay his travel cost and live on what was a then small income at that time. After a jobless spell, he got another job and did a change of circumstances and the assessment was then corrected as he no longer had a need to high travel allowances and he paid the CSA.
He met a woman and got another job closer to her. The CSA given a change of circumstances. The CSA refused to let him pay his new tenancy because it was too high, beyond his means, so they charged him maintenance on the basis he was still living at his old address under his previous tenancy.
He moved again 2001. A job opportunity overseas, well paid and notified the CSA, who replied with a 'no change' decision notice. That is the last he heard from the CSA directly. There is a 2003 dated photocopy (or faxed) bailiff notice with his correct name but a completely unknown UK address demanding child maintenance. The UK address is not even in his addressbook.
No liability order and it seems he was nonethewiser of it. I don't know how that stands with s.14 of the magistrates courts act. The CSA says there is a second liability order in 2008, but there is no evidence of it.
He came back to the UK in 2013, was unwell but nothing diagnosed at the time. Died 2015 from a spinal tumour leaving a will with me as executor and trustee.
After seeking advice from multiple sources, I cannot honour the CSA demand because they give no evidence the Limitation Act does not apply. I have to follow Parliament and it says the liability became unrecoverable after 6 years the course of action accrued.
I gave a wrong postcode in their data protection security check, and yet the continued to discuss the case with me. I think they were unaware data protection does not apply to the deceased. It was quite an experience dealing with these people. Even contradicting their own advice when they found it had become inconvenient.
The beneficiaries are the maintenance children named on his CSA paperwork, so it would appear the money demanded is not destined for them. The girls are adults now, affable, but their mother threatens to sue the estate. Quite acrimonious.