clients are a married couple who are both severely disabled. Mr H gets HRMC & HRCC. Mrs H gets SDA, HRMC & MRCC. They get some IS as well.
Mr H used to get SDA. He tells me it stopped in 1996, round about the time they got married. He cannot recollect being told a reason for it stopping - he thought at the time it was due to his marriage.
I asked DWP for the reasons but they say his documents have been destroyed and suggest it could be due to an improvement in his condition. Can't see that is very likely and in any case he would have automaticaly got SDA, at that time, on grounds of HRCC ( I think!).
I was hoping to get them underlying entitlement to CA and thus Carer's premium without losing their severe disability premium.
I was hoping to get this SDA decision corrected if it is an official error - but can I prove it?

I agree- from what I remember about those dim & distant days, HRCC was automatic route to 80% disabled. I think the question is not so much whether you can prove it was an official error but whether they can prove it wasn't. I think, if it was me, I'd request an anytime revision on that basis and put the ball in their court. There must be a record of the decision somewhere- after all, 'old' decisions have never prevented the DWP from suddenly deciding to recover overpayments years after the event...