So, after a lot of thought, I ran the address through Google Translate, used that as the address to buy postage, and stuck the address in Thai onto the box next to the Royal Mail label.
Anyone want to bet on the likelihood it will reach its destination?
later - and as if by magic, twenty minutes later the guy got back to me with an English translation of his address, which turned out to be different enough that I doubt that the Google version would have worked. So I've filled in the form to cancel the postage I bought on line and get a refund, bought another lot of postage with the correct address, and hopefully that will be it.
Unless of course something else goes wrong and I have to untangle this mess...
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