interesting Thin Lizzy history : http://www.roisindubh.com/history2.htm
Phil felt convinced he already had a hit up his sleeve with a song called 'Black Boys On The Corner.' What they needed was a B - side, and during a rehearsal session they thought they had found one. Phil started strumming a traditional Irish tune called 'Whiskey In The Jar.' Eric picked up his guitar and jammed and along and soon Brian Downey joined in on drums. The whole piece started steaming away when Ted Carroll walked in and immediately proclaimed he was hearing a hit single. He begged them to put it on the A side - and that's the way it came out in November 1972, with 'Black Boys On The Corner' on the B- side.
Said Phil: "We just wanted to put it out for a laugh, for the kids at home.
The small town boys didn't think that having a pop hit with a revamped Irish folk song was the right way for dedicated musos to carry on. They could see themselves ...always hunting for another hit to survive. The sudden rush of activity was also hard for them to swallow.
it didn't matter what we were playing on stage. People aren't listening until we played 'Whiskey in The Jar: and then they were jumping up and down.. Then they went home. They just came to hear the number one.