>Is there anything to stop an artist, whose work is held by Celtic Music, recording some or all of the songs again, perhaps with a slightly different arrangement, and have them issued through a different company?<

These would of course be totally different albums. The artists are older and not all of the are still performing, or indeed still with us. And they wouldn't have Bill Leader presiding over the recording. To these ears, 70s albums on Trailer sound nothing like modern folk albums. I own quite a few Trailer releases on vinyl and there's something quite special and magical about these releases that to me has generally been lost on most modern folk albums. There's a rawness and directness and lack or artifice that would be hard to replicate.

I just wish more current folk albums sounded like Trailer releases, really...

Also call me a purist, but (for example) there's an ocean of diffrence between Mike & Lal Waterson's Bright Phoebus and the tribute album that came out a few years back. Not a value judgement, but the two things aren't the same.