What are the requirements for applying for a 3-month Non-O visa in the UK for retirement in Thailand?

Sadly

@Mark ***********

the fact you have a condo/bank account here cuts no ice visa/extension wise.

BUT

now that people pointed out the requirements to get that 90 day Non-O issued in the UK before you come here I'd say you're way better off just getting a single entry tourist visa from the consulate comin' here, getting the 800K baht in a thai bank account in your name only and applying for a 90 day Non-O visa IN-COUNTRY (doesn't require any insurance at all) for 2000baht and then after that getting the year extension 2 months later for 1900baht

Don’t apply for the retirement visa from abroad.

Do it in country.

Preserve your options.

I have just successfully applied for a Non O based for the reason of retirement in the UK and none of questions was about whether I was married to a Thai. The drop down menu asks the reason for the Non O, retirement and marriage are two. Make sure you choose the correct one. It did ask me for the address I am staying in Thailand.