To be more specific, it was a one year extension of stay based upon retirement.
In 2019 I left with a valid one year 'retirement' visa and a single re-entry permit.
Due the uncertainties of travel at the beginning of 2020, I decided to stay in UK.
When all entry restrictions were lifted in 1st July this year I returned to Thailand in September.
All my previous visa stuff was by now expired.
I had taken the opportunity to get a new passport in the UK and as my 800k has been in the bank for many years, I was issued with a fresh 'retirement' visa.
As I'm no spring chicken anymore, I'm was anxious about changes in the immigration system whilst being away.
Thanks for the always helpful replies.