The 1993 EU Copyright law is here.
Article 5 appears to be crucial:
Critical and scientific publications
Member States may protect critical and scientific publications of works which have come into the public domain. The maximum term of protection of such rights shall be 30 years from the time when the publication was first lawfully published.
Also of interest: “How long does copyright last?” in the document entitled Ownership and duration of copyright published by the UK Patent Office:
… published editions are protected for 25 years.