The UK company has revenue and pays corp tax, but I don't think this is what they'll be looking for, won't they want to see salary going from that company into a UK bank acc?
Company was registered years ago, income was paid via consulting under a Thai registered company for years. I have the payslips and tax returns for this, but this won't really prove income was generated via the foreign company, just paid out from a Thai company.
I own the company in the UK, so getting a letter saying I will be consulting for a company I own that has no clients inside Thailand is not an issue. But I do have a history of working for a company inside Thailand, which I guess I would need some letter saying that position has ended and the Non B cancelled?
I'd be working for my foreign company that I own, so income will change from salary from a Thai company to working as a consultant for my foreign company.