I'm going to say that it would not be considered a true "trad" by my definition simply because it is one that was written during the heyday of the Irish/Folk revival in the 60's. My research a few years ago into what would constitute a trad song was very organic...there wasn't a distinct line between trad songs and other works but generally the trad songs are older, passed down in the oral tradition and were not written down initially. The written versions of trad songs came about as a way to preserve them. So many lovely tunes from the 60's and 70's were written in a trad style, but simply don't have the age and the history that trad songs do.

Now that I have said that, there are any number of other folk who will give you a different opinion lol!