Same same. My IO asked for it and I could not produce...she went online checked my entry and wrote a duplicate.. Moral speak to your local IO before it becomes a problem.
So if he were to transfer money from his thai account to UK account - HMRC wouldnt be questioning the source of funds ? Why bother? He has a Thai bank account so I Imagine he must have a debit card, just take out the cash from an atm in the UK as and when - being an off system card (not registered in the UK) it is not putting up any flags. If he needs to put it into a UK account just pay the cash in and if someone DEMANDS to know where it came from, walk them over to the nearest atm and draw out another 500, He works in Thailand - he earnt it in Thailand and has been paid in Thailand, it is of no business of the UK authorities.
Savannaket Laos over the bridge from Mukdahan - Embassy opens from 9.00 to 12.00 pick up visa 2.00pm next day - Opposite is a copy shop run by Tony - he will complete all your documentation ofr 100 Bt - if you forget your photos he will do that too. Enjoy a couple of days in Laos.