I assume very unlikely in this case but UK overseas workers can make voluntary contributions to obtain a UK state pension.
...that would not be payable until pension age.
What? He entered at some date and never did his 90 day reports so you can easily identity this in the database.
What? VE entries do not have a 90-day report requirement!
His UK family may continue to support them. As a Non-Thai resident the humanity aspect is something that he should have considered years ago, it is not the Thai authorities responsibility...imagine the chaos if that were the case - have a child and get to stay visa-free.