Without question, I think it is the stories that grab the attention of the general concert audience, and they are enhanced by the beautiful, simple but descriptive language used in the ballads.   I try to give enough background to put the songs in context and if I can find a few anecdotes I'll recount them too. For example, when I sing "Thomas the Rhymer" I might mention his famous prediction about Alexander III's death. Sometimes it helps to have a "flow" too. For example, I sang "House Carpenter" followed by "John Reilly" followed by "Billy Taylor". That enabled me to spin a little yarn about how when people went to sea they might be gone a long time and you'd have no word from them, and they might not come back at all. So what did you do - remain faithful and wait for them ? Find someone else? And if you did, what if they came back? And what about the intrepid young lady who decided to go looking for her sailor lover, and found he'd married another... So the whole concert becomes a narrative. For example, "Geordie" - heartrending injustice and cruelty for somebody who only poached the king's deer. Then followed by "Young Waters" - my god the man's only crime was being good looking, and he was beheaded! Then on to "Willie of Winsbury" - well being good looking saved his skin! And the audience is surprised and delighted by the happy ending.

In some ways it may be harder to sing to a 'ballad savvy' audience. The general audience is surprised and delighted at the twists and turns in the stories. An audience that already knows most of the ballads will be looking at whether or not you can uncover a new and interesting version they hadn't heard, or if you sing a version they know they'll be comparing you to somebody else. And there's no suspense, since they know most of the stories.

An academic lecture is a different matter entirely, and something I wouldn't attempt to do.