Today I received a letter from the DWP. I was amused to see that they had used the stamped addressed envelope I included for them. They don't usually do so. At least my stamp did not go to waste.
They stated in the letter that I had been on Income Related Employment & Support Allowance.
The letter did not say so, but this will explain why they ceased my ESA when I received my divorce settlement. I should have been on Contributions Based Employment & Support Allowance. As such the money should not have affected my payments, and I should be able to reclaim a few months worth.
It seems they believe I started claiming in February last year however, so I only missed two months of payments. I believed I started claiming in April, I am however happy to assume that their records are correct. As such, if I fail in my endeavour to reclaim the money they owe me, I have not really lost all that much.