I received a reply from the Pali Text Society:

>>G.P. Malalasekera's Dictionary of Pali Proper Names was originally

published in the Indian Text Series, a publication series of the pre-
partition Indian Government. At partition in 1947 all property of the old
Indian Government was divided between the governments of India and
Pakistan. When we wanted to reprint it in 1960 Miss Horner asked both
governments for permission to do so, was given it. At the beginning of our
edition we say, "This volume has been reprinted with the kind permission
of the Govt of India and the Govt of Pakistan". As far as we know the
copyright still resides with those two governments, so strictly only they
can grant permission to reproduce the text.<<

Not sure where we go from here. Any suggestions?