Much to agree with in what you say there Dave, but the following should have been qualified:

"As long as the song is contemporary to the event it tells us a lot more about how those people affected by the event and its aftermath felt and the ordinary man's views than any dry tome in a mainstream bookshop ever could."

Would also add the ordinary man's views is a bit too far and too great a claim to make as the ordinary man, back in the day. in nine instances out of ten would not know that anything had occurred at all.

"Folk songs contemporary to the event are, in my opinion, a good source of how some people thought, reacted and described events."

You have it spot on when you state - A window on to times gone by that plain old facts can never show.