Wife has a ten years UK visa. However, as you know a Thai passport is only good for five years. Will we have a problem presenting both passports at Suvarnabhumi check-in, ie the new passport with no visa and the expired passport with the valid visa.

 

Do we need to get it 'endorsed' into the new passport before we go?

 

PS, I did do a 'search' first and it turned up 1.1million links!! I think the word Thai was the problem.

Providing the passports, and of course the visa, are in the same name, then you should have no problem.

 

My wife has never had a problem checking in at BKK or on arrival at the UK Border, when her previous visa was in her expired passport.

 

You can get the visa transferred to the new passport, but it costs a fair bit and is not neccessary.

 

https://www.gov.uk/transfer-visa

Should be the same as a Thai visa in an expired British passport; present both at immigration, though it will obviously be more relevant at the UK end than the Thai one. 

Dont forget both passports old and new show both no problem