Hi, welcome to Just Answer. I will help you with your question.
Copyright in works with an unknown author (as seems to be the case here) expires 70 years after the publication of the book (s.12 of the copyright Design and Patents Act 1988). So, it is now out of copyright and you'd be free to copy it and reproduce it as you see fit.
If, however, the author is identified, then copyright expires 70 years after the authors death.
Ah ... yes, he will be an identified author, and this scenario is address by s.12(3) of the 1988 Act. Basically, because he is identified in the 1090 version, then the 70 years from date of death will apply. So you need to find out when he died.
The different publisher is irrelevant.
Does this answer your question?
If a known (or fairly known) author, you should be able to make some headway with google searches. If not, then you might be better off contacting the publisher and asking them.
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