I checked this out some time ago, and the position is esentially as
stated by Pete Joseph, the copyright does lapse. However there are
complications. Firstly, as Pete suggests, anyone who makes a new
arrangement or compilation of a map (simply by scanning it) creates a
new work as far as copyright is concerned and are entitled to 70 years
from that date. This also applies to the printed reproductions of old
maps of interesting areas which you can buy, they are photographically
reduced from the originals, but constitute a new work. Sadly, some
libraries will reproduce old maps for you but stamp them with a
copyright. The fact, unfair in some circumstances though it may be, is
that the copyright does effectively belong to the person who makes the
fresh copy. Understandable in the case of printed copies, they don't
want pirate copying, and old-maps.co.uk has a web site to run and fund,
but sad nonetheless, as in my opinion such information should be freely
available. Not a good idea to copy illegally from old-maps (some of
their scans are of abysmal quality, bits of maps not joined together,
and a lot of spots and blemishes, so it would be very obvious where it
came from...). I would never condone copyright violation, it is simply
theft.

If you can borrow an original, or buy one (there are specialist
suppliers of old maps as I am sure you know), and photocopy or scan it
yourself, then only the 50 year (crown copyright) or 70 year (everything
else) rule applies so you can do what you want. The same applies if a
library prints you a copy without any stamp, or accompanying paperwork,
or has not made you fill in and sign a form, limiting your rights.
Please, dont do as others do and apply a copyright, either declare it to
be in the public domain or give it a licence of some sort, such as
applies to free software for example, so that others can also benefit.

I have a few old maps myself, when time permits and I work out a
sensible user interface, they will be appearing on a web site, and will
be licensed for use by anyone. I think that is the correct way to do it,
and i hope that others will feel the same way about any maps in their
possession. The one that might give some readers of this list something
to look forward to is a 1952 map of Leadhills and Wanlockhead, 25000
scale (or was it 2.5 inch?), I have a genuine, crown copyright-expired
original, in pristine condition. I just need the time.

Alan Campbell