"bewildered by singing style and songs on offer from one Peter Bellamy."
.,,.

In Pete's case was surely his style, which notoriously was 'Marmite' ("love it or hate it"), rather than his songs, which were unlikely to have been very different from those you report their having previously enjoyed from MacColl and [albeit probably in other versions] Seeger, which was/were found bewildering. As Pete was too idiosyncratic an exemplar to cite stylistically, I am not sure your in-laws' experience of him will actually add much light to your somewhat eccentric views of what the traddies "think they have got right". I am blowed if I can make out precisely what you think it that they "think they have got right".

In fact, to be honest, I'm not at all sure where you are coming from in your observations at the end of that little anecdote,

"the traddies are sure they've got it right, i'm equally sure they haven't. however they have all the power and prestige of the press, the university system, the bbc. i still think they've got it wrong."

or how you think the experience you relate illustrates the points you urge -- whatever they may be.

≈M≈