This sounds quite easy. I am in Thailand on a 30 day visa exemption stamp and have got my new passport and the old passport. I intend to do the stamp transfer and will see how it goes. I see some say I should make a police report too and get a letter from UK embassy asking for stamp transfer. I didn't lose my old passport and so not sure what to report at police station. I just wanted to order a new passport as the old 1 has only a few clean pages left. And the UK passport comes not via the British Embassy but via the outsourced VFS centre in Bangkok.