How do I transfer my Thai visa from my old UK passport to my new one?

To transfer your Thai visa from an old UK passport to a new one, first, ensure you have your old passport, new passport, and a letter from your consulate confirming the passport change. Bring copies of both passports, the letter, all current Thai visa copies, and the TM6 form. Then, visit the local immigration office to complete the transfer, which should take around 15 minutes.