It's not just the famed sax chorus, it's not just the lyrics, it's Rafferty's voice and the delivery. You don't need to be told quality is quality, you just know it.
UPDATE: A good friend of your humble scribe's (and proud of his Irish blood), reader 'M' sends this in. For what it's worth, I agree:
From the BBC link: "Gerald Rafferty was born in Paisley on 16 April 1947, the son of a Scottish mother and an Irish father, who taught his young son to holler out Irish rebel songs."
I shudder to think of all the fine music that may not have been created had the Irish and their stout oaks not presented an irresistible temptation to our eastern neighbors...a terrible yin and yang, but I can tell we're finally wearing you down...(that's a textual representation of a friendly and impish wink). We are grateful for you teaching us to speak English and have ever endeavored to return the favor by improving it ever since.
Tiocfaidh Ár Lá