SO'P,it sounds as if you were fortunate in your music teacher. Like Ian Mather, I was taught by an old-fashioned music teacher who succeeded only in turning me off classical music and teaching me nothing about music theory. It took another teacher, from the French department but an enthusiast for Handel, who let us throw away the scores and listen, and who explained counterpoint by working backwards from boogie-woogie. He was able to put across his enthusiasm and opened my eyes and ears.

To turn to Ian's other point, there should be no need to fear twerps pulling you up if you sing traditional songs. It's when people sing other stuff that they risk treading on thin ice. Different clubs and audiences have different ideas about what they find acceptable, and what might go down well with one audience might be anathema to another. You have to know your audience.

If you sing a traditional song at a folk club then you will still not be immune from the twerps who think they know everything, but you can at least be sure of your ground nd confident that you have a right to sing that material.