Help to ID this coin

The coin is 30mm diameter the metal I do not know. One side shows the emblem for the golden jubilee of the King Of Thailand Rama XI. The stamping is not of the Thai script. The other side I have not seen before. All the coins I have for that year all depict the king's portrait. Any help appreciated.     

Do you have any better resolution pictures? I can't quite make out the characters on the reverse.

The reverse is similar to the Thai 50th anniversary coins, except for the Chinese characters at the bottom.
Can't quite make them out, but it says something like "after 15 great years" or "15 big years lost", but the translation is going to be way off if I have any characters wrong.

The obverse too seems to have Chinese characters, but again I can't make them out.

Token


Chinese characters from right to left on both side ....

obverse : 普天同慶 (National Celebration)

reverse: 泰皇登基五十年大慶 (The emperor of Thai ascends the throne 50th anniversary)

Ah, had the characters the wrong way round!  

Thank you very much for your help,
Pilford