Foreign children born in Thailand
If neither of the parents is Thai, then your child will not get Thai nationality – the child will have the same nationality as the parents. You should contact the consular section of the British Embassy to find out about the documentation required to register the child as a British citizen. The British Embassy number is 02-2530191, or visit the website at http://www.britishemb.or.th
Consular Office, British Embassy, Bangkok.