Not for their offshore / expat / international accounts
that wouldnt make sense
An example from NatWest International account information page (my emphasis).
"To apply for one of our bank accounts you must meet the minimum age, residency, balance and/or deposit requirements. View the relevant product page to find out more."
and
"To apply you must be; aged 18+, resident in one of our listed countries and meet our minimum balance, salary or deposit requirements.
Please note: all accounts opened through our online, digital application will be based in Jersey and therefore bound by Jersey Law."
"Residential requirements
Our International Banking service can help customers who are resident in the following countries:
Austria, Bahrain, Belgium, Bermuda, Canada, China (Expats only), Denmark, Finland, France, Hong Kong, Kuwait, Norway, Oman, Qatar, South Africa, Sweden, Switzerland, United Arab Emirates, United Kingdom (Non-domiciled only) or the United States of America.
Please note that not all of our products and services are available in all jurisdictions and some are available on a limited basis only due to local regulatory and legal requirements."
Furthermore:
"You can apply for an International Select account if you are:
aged 18+, and resident in one of our listed countries, and open the account with a minimum deposit of £25,000 or pay in a mandated salary of £40,000."
Since Thailand isn't on their pre-approved list, it will be up to the applicant to ascertain what proof of being non-domiciled in the UK will be accepted by this bank. Also, most pensions will fall well short of the monetary minimums required to open and maintain the account.
Good luck!