Pre-requisite to Answering: Chiang Mai (British Passport)
Has anyone used the embassy issued personalised Covid-18 Extension letter at Chiang Mai immigration?
(I was issued a personalised version of the letter today by the UK Embassy Bangkok)
I asked about having to have an original copy, and the UK embassy assured me a copy is suffice (with personal details listed) & for immigration to call them if they don't accept.
(Sorry if this has already been answered in a comment.)
Thanks,