Just about to get a new UK passport , I have a two month visa , and have had it extended for 30 days , do I need to do anything before leaving Thailand , or will the old visa (cancelled) still be ok with the stamps in it

It will not be a problem if leaving from an airport. At some border crossing they will charge extra to have the stamps transferred or send you to a nearby immigration office to do it.

Does the OP have a Re-Entry Permit for his current Permission To Stay? If not, he should get one, or there will be nothing to transfer.

15 minutes ago, mahjongguy said:

Does the OP have a Re-Entry Permit for his current Permission To Stay? If not, he should get one, or there will be nothing to transfer.

he only has a 30 day extension . maybe no need to protect that short of a time

16 minutes ago, mahjongguy said:

Does the OP have a Re-Entry Permit for his current Permission To Stay? If not, he should get one, or there will be nothing to transfer.

Why would he need a re-entry permit for the few remaining days he may have left on his 30 day extension.

There is still a entry and extension stamp that needs to be transferred before he can be stamped out of the country in the new passport.

I thought the OP was implying that he wanted to preserve some aspect of his visa + stamps. My error.

Thanks all , no , just checking that there would be no problem exiting Thailand , as I will have a new passport , and my existing one with the entry stamps apparently gets cacelled on the issue of my new one , just double checking that I am OK to get out !!

23 minutes ago, jkthai said:

Thanks all , no , just checking that there would be no problem exiting Thailand , as I will have a new passport , and my existing one with the entry stamps apparently gets cacelled on the issue of my new one , just double checking that I am OK to get out !!

You can have the stamps transferred at a immigration office. They will do a annotation of the visa you used for entry, entry stamp and extension stamp in your new passport.

If leaving from an airport it can be done on departure from the country. Some border crossings will charge for the transfer or send you to a nearby immigration office to do it.

ubonjoe , much appreciated thanks