Is The Ghost and Mrs. Muir in the public domain?

Answer 1

No. The book was published in the UK in 1945, meaning that its copyright duration is governed by the laws of that country, i.e., 70 years after death of the author.

The film version has its own copyright with its own duration.

Answer 2

One of my favorite books, The Ghost and Mrs. Muir, was first published in 1945. The author is Josephine Leslie, writing under the pseudonym of R. A. Dick.