I always thought it peculiar why this is done. If your name isn't Gaelic in origin or you're not from a family with an Anglo-Irish name that Gaelicised its surname why change the name at all. If I go to Italy, and my name was Paul Murphy, they wouldn't change it to Paulo Di Murphio. If I went to Spain my name wouldn't change from James Hennessy to Jaime Hennessez, in Holland it wouldn't change from Joe Kelly to Jo Van der Kellyklamp etc etc. Why is it done here. Its ridiculous.
Another thing:
Smith is always translated to Irish as Mac Gabhan (sp?)
Many people originally called Mac Gabhan were anglicised to Smith, so there is some justice in that. But many, indeed maybe the majority of Smiths today are not Mac Gabhans. They are descended from "foreign" Smiths.
If your name is Smith, and you go to live in Italy, should you translate it to Ferrari (which means Smith)?
Mind you that would be cool.
If there is a future, it will be Green.
It may have been so Hilmannhunter1 jnr wasn't the only child in the class with a gaelicisied name. It sounds dumb, but you know how kids can be.
"Authority that cannot be questioned is tyranny and I will not accept tyranny, any tyranny, even that of heaven."
- Terry Pratchett
It's not quite the same but it's the closest I could find. Ambrosio O'Higgins, Marquis of Osorno - Wikipedia, the free encyclopedia
I'd say the teacher has always done it and did it without thinking it would cause offence. It would have been polite to let the school know in advance that you didn't want your son's surname Gaelicized for any reason.