Anyone should feel free to do traditional material but once recorded it should be attributed as trad. arranged x. The copying of someone's arrangement for gain is not nice, an artist may have put considerable effort into making that arrangement/interpretation their own, but can an arrangement be copyrighted?

Countess Richard makes the point of < deliberately altering or rewriting the words and tunes of traditional songs while keeping, more or less, in sympathy with the orginal. > This is perfectly acceptable and Martin Carthy has said as much himself. Singers have altered songs to suit their liking for centuries and is part of the evolving tradition, it is also one reason why there are so many variants of a song/tune.

The song in question - trad. arranged Jones.