If they only died a week ago, assuming the war was still in progress, was Jersey still occupied? I mean, the new family moved in as if life was normal, even to the point of having a seance. It didn't seem like life around a war was happening. Maybe grace was really off by her saying a week ago?
shareThe ghost and the real people are living in two different planes.
Time is different for the living and the dead.
The ghost are only sometimes aware of the living people.
The war isn't still in progress.
Grace very explicitly says that the war is over in her last scene with her husband. It's also noted at the beginning that the war is over. I can remember two instances: Grace mentions that during the entire German occupation, she never allowed a Nazi into the house, which implies that the occupation has ended. There's also a few lines where she talks about her husband not having returned, even though the war has ended.