The laws regarding intellectual and moral rights are to protect the owner of copywright. In the case of Mr Bulmers re'issues it would appear that he owns the copywrights in question. MCPS/PRS and other collection agencies do not intervene in disputes between members and it is therefore up to the artist or artists concerned to regain the rights to their work through the courts. If any of the artists have recording contracts with Celtic Music and the terms of these contracts have not been honoured then they have a case in law under breach of contract. I have no idea of the position with regard to music catalogues aquired from other labels.