Alberto,
Perhaps you'd like to name one Irish song that the English or Scotch have claimed as theirs.

The song under discussion here is clearly set in Ireland and in the earliest extant version, as mentioned by Bruce above, the lover is most definitely a jockey, nothing to do with soldiers. However it was widely printed in England and as already been said the version being currently sung is based on a version printed in Scotland.

There are many songs common to England, Ireland and Scotland. In most cases it is impossible to determine in which of the countries a song originated. As someone has already mentioned these sort of songs passed freely back and forth between the countries with a common language and that includes North America. Many of the songs nowadays taken to be Irish are in fact by American authors writing FOR the Irish in America.