mkc1959 : http://www.multiplecitizenship.com/wscl/ws_THAILAND.html
mkc1959 : That link explains Thai citizenship laws. I am still working on this response.
I assumed they would be dual?
born in T now residing UK
mkc1959 : http://www.multiplecitizenship.com/wscl/ws_UNITED_KINGDOM.html
mkc1959 : This link explains English citizenship.
so what is your conclusion?
mkc1959 : The Thailand citizenship act indicates that it does not recognize dual citizenship.
mkc1959 : So with the exception the children can have dual citizenship until the age of 18.
mkc1959 : Please let me know what additional questions you have.
mkc1959 : DUAL CITIZENSHIP: NOT RECOGNIZED. Exceptions:Child born abroad to Thai parents, who obtains the citizenship of the foreign country of birth, may retain dual citizenship until reaching the age of majority (18). At this point, person must choose which citizenship to retain.
can they only have Thai passports until they are 18?
mkc1959 : Yes unless at age 18 they choose to only hold Thai citizenship.
NB they were born in T to British father Thai wife, now resident England - some of above is irrelevant? can you summarise present position?