1) Is a letter from your embassy in Thailand stating that you intend to retire there still required? Does it require any special eligibility or checks on the part of the (UK) authorities?

2) Can I travel in and out of Thailand at will on this visa without suffering cancellation?

3) Can the renewal each year be performed in-country?

Thanks to all.

1) Is a letter from your embassy in Thailand stating that you intend to retire there still required?

no

Does it require any special eligibility or checks on the part of the (UK) authorities?

Only if you apply for the O-A in the UK

2) Can I travel in and out of Thailand at will on this visa without suffering cancellation?

yes but you will need to get a reentry permit after you get the extension of stay based on retirement or if you only have a single entry "O" visa.

3) Can the renewal each year be performed in-country?

yes

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