Unlikely to be asked by immigration but likely to be asked by the airline at check in - most likely in Dublin if they are checking in all the way to Thailand.
Ok, I never heard of such requirement in my 20 years here, but will stand corrected. He said he was going to the Singapore consulate so I stated what I know having gone through the same in Singapore.
Just to reiterate my last post, having just read other comments. Please do not spend money on going to other consulates, other than what’s local to you. I’ve done non o visas in Penang, Singapore and HK, and I’m from the UK. Due to work circumstances I’ve never converted them to extension of stay until now- took me 2 visits to Pattaya immigration to ensure my documents for the extension were right! So if you need any pointers just shout.