It's ok to be a log for the Wickerman: however big the fire, there's always someone round the corner happy to piss on it.
Meanwhile...

Is there a single musician, vocalist or instrument that everyone can agree on?

Now then, don't be silly.

And it depends if you mean we all agree they're blooming marvellous or all agree they're shite.

What we're looking for is someone who's a traditional singer and a singersongwriter (or neither); as old as the hills and the new kid on the block (or neither); is part of the folk establishment and is a shunned, reviled rebel (or neither); is an inspector in the folk police and and a hunted fugitive from justice (or neither); has paid their dues round every godforsaken folk club in the land and wouldn't piss on the last folk club standing if it was on fire (or neither); is playing the latest cutting edge ambient folktronica and has taylored their entirely career to getting onto 'wonderful' radio two (or neither); is a proudly amateur folk singer who thinks turning professional is a betrayal of the entire movement and is a pro with major label backing and a brilliant PR machine (or neither); thinks 1954 is the holy word of god and a random year halfway through the last century (or neither) or is anywhere (or nowhere) on the continuum (or not) between the two (or more). (Or less).

And their name is....