Their legitimate reason for enquiring about the source of funds is an anti-money laundering question that they are obligated to ask by UK authorities and as long as the transfer was legitimate an account holder should have no issue answering. Those making legitimate transactions do not need to be "forewarned" or "forearmed".
Don't blame the OP. He heard about it just now from a video that was uploaded to YouTube yesterday.
Why not blame him? He knows that this happened 16 years ago in an airline that hasn't existed for 13 years.
All of them. Do you understand the concept of treason?
Yes, I do; do you understand the concept of something being "trumped-up", not to mention the concept of justifying your trumped-up "trumped-up" assertion?
Who says he did not want his wife to have this.
Quite right, he may have been aware of the will situation when he married her and it was his intention.
"DO leave sufficient funds (something 10k THB) in the account". That's not necessary as long as the account has some movement, I think every three months. I have a couple of accounts that very rarely get used and never have more than B500 in them but I make a transfer in and out each month to keep them active. There are no additional fees for keeping low balances.
Thai banks do not transfer accounts between branches, you have to open a new account. Keep the original account open, it's never a good idea to close a bank account that can be kept active.