Thanks for your reply. The surname on the birth certificate simply omits an S, for my grandfather and his parents. I just don't know whether to input this misspelled name where it asks for name on birth certificate, or put in the correct spelling, effectively fibbing, as on all the other ...

I'm applying from the UK, England, for Irish citizenship, registration of birth first, through my Irish grandfather. Does that make a difference to how I fill in surname on birth certificate? Thank you

It's misspelled on his birth certificate, as well as his parents' surname. Correct on every other document. When filling in MY application do I put the misspelled name as surname on his birth certificate, and then change of name as correctly spelled. Or do I put it as misspelled without a change of ...