One of Ireland's greatest songs, 'Danny Boy,' turned 100 in 2013. To mark the occasion, a BBC4 television documentary, 'Danny Boy: The Ballad That Bewitched The World,' explored this great, timeless anthem.

Although the song is most closely associated with the world's Irish communities, it was, in fact, written by Englishman Frederic Weatherly.

“I believe that for 'Danny Boy' to have had such a huge cultural impact, it has to have tapped into the fundamental stuff – emotions and experiences that affect us all. 'Danny Boy' is certainly about loss, departure, even death. But crucially, it’s also uplifting – offering us that tantalizing hope of a possible reunion with the departed," the film's director James Maycock told Mojo4Music.com.

“So there is definitely an emotional equilibrium, a ying and yang, at play. Indeed, in the film, musician Joe Jackson explains how the song itself shifts from major to minor keys. Just as the 'Danny Boy' lyrics flit between sadness and optimism, so its music is melancholic but also contains a hugely rousing, life-affirming chorus. Intriguingly, the highest note of that big chorus is reached on the line – ‘come ye back’ – exuberantly underscoring the chance of meeting again, accentuating the positive.

“Inevitably, the song has resonated most with those who have experienced loss – loss that includes ‘losing’ one’s own country – but who still believe in a bright new day. So 'Danny Boy' means a great deal to members of the Irish diaspora forced into exile, particularly in the States. Black Americans, too, have recognized the loss-hope dynamic in the tune. It’s cathartic, like the blues.

“What particularly intrigued me when I started making this film was the number of versions recorded by country artists. It didn’t feel like a coincidence. I knew they weren’t covering 'Danny Boy' just because it was a standard. They had to be tapping into the heartbreak center of the song.

“In the film, I use Johnny Cash’s 1965 recording of 'Danny Boy' as the prism to investigate the appeal of the song to country artists. His daughter, Rosanne Cash, speaks of why it’s such a natural fit for poor white southerners and their tough, intense lives. While Larry Kirwan of the Irish-American band, Black 47, explains how 19th Century Irish immigrants brought their fiddles and music to the Appalachians. This subsequently influenced bluegrass – then country. With an ancient Irish tune, the 'Londonderry Air,' at the song’s musical heart, it was all beginning to make sense.

“Songs like 'Danny Boy' that last 100 years are rare. They appear simple but are beautifully complicated. You need a bunch of keys to unlock the mysteries of 'Danny Boy,' but I believe one of its most essential elements is its emotional dialectic – loss and hope, joy and pain, sunshine and shadow – and these lie at the very center of all our lives.”

Here's Andy Williams singing the much-loved tune:

And if you think you're already a pro and know all there is to know about Danny Boy, especially its lyrics, why not try out our "Danny Boy" quiz? Be sure to let us know how you do in the comments section.