I have now had chance to browse on
http://www.ahds.ac.uk/copyrightfaq.htm#faq2 and it says ...
(1)
Artistic Works
Graphic works (painting, drawing, diagram, map, chart, plan, engraving, etching, lithograph, woodcut), Photographs (not part of a moving film), sculpture, collage, works of architecture (buildings and models for buildings), and artistic craftsmanship (e.g. jewelry).
Lifetime of copyright protection: Authors/creators life plus 70 years after death.
(2)
Crown Copyright
All works made by Her Majesty or by an officer or servant of the Crown in the course of his or her duties
Lifetime of copyright protection: Published work: 50 years from the end of the year when first published. Unpublished work:125 years beyond the year it was created
This information would suggest that the copyright has expired on some of my list. Just in case, how would I be able to track down the holders of the copyright or check (in the case of Crown copyright) if a work has been published?