@Ian *******
" just change "India" to "Thailand" and there you are! . . . . "Passengers may request the customs for issue of an export certificate at the time of their departure from India, in respect of jewellery carried by them to facilitate its re-import subsequently. If an individual does not intend to bring back the ornaments within three years, then an export certificate may not be required. Therefore, any amount of bonafide gold can be taken from India to UK as personal baggage.
However, as per UK laws, certain customs/import duties or taxes may be applicable on such goods. Passengers have to declare the jewellery they intend to bring in UK to the custom authorities.
Personal allowance rules apply to any goods you have bought overseas and are bringing into the UK. Goods (for your own use or to be given as gifts) commonly known as ‘personal allowances’, are not subject to taxes and duties. You can bring in such goods worth up to £390. Beyond this, you need to pay tax and duty on the total value of the goods and not just the value above the allowance. Therefore, it is advisable to declare the same on UK government websites ,which also assist in ascertaining the amount of tax to be paid (if any)."