We are not expressly told why the Drovers left, but it is easy enough to work out from the information we are given. The story is set in the time of the Second World War - 1941, to be precise. At this time many mainland British towns and cities were liable to be bombed, so that families would evacuate to the countryside. Mrs Drover has returned after a recent bombardment to collect some family belongings from their old residence.
The streets around the house are more or less deserted, which would not be the case, particularly on a sunny summer afternoon, in normal times. They also bear the signs of war-devastation; and Mrs Drover notes of her own old residence that 'There were some cracks in the structure, left by the last bombing, on which she was anxious to keep an eye.' Her own house, then, has not escaped damage, and it could be said that the cracked house also reflects her own somewhat troubled state of mind.
Mrs. Drover returned to a London that had been badly damaged by bombings. As she walked toward her home, she noticed the "broken chimneys and parapets." In 1940 and 1941, the Nazis bombed London and other British cities by airplane. Many buildings were damaged. Some people lost their homes to the German bombs. Others found their homes damaged by the bombings. Residents who were able to chose to leave London to escape the stress and danger of the bombings. They went to the English countryside to live. This was what the Drover family did, leaving their house to be watched over by a caretaker. The Nazis strategically chose to bomb cities and large towns, which were densely populated.
Once Mrs. Drover reached her house, she found that her front door had warped and "there were some cracks in the structure, left by the last bombing." After she left her house, she observed "the unoccupied houses... [which] continued to meet her look with their damaged stare." As she walked through her neighborhood, she found there to be a "silence exaggerated this summer by the damage of war." Many of the houses were empty because other neighbors had fled London.
There was significant evidence in the story of how much London changed after the bombings. These repeated descriptions of the damage and the mention of empty houses showed the impact of the bombings. These drastic changes revealed some of the reasons why the Drover family chose to relocate to the country.
In "The Demon Lover," the Drover family has left London for the countryside because of the war. The city has been bombed many times, and the people who live there feel safer living in the country. Mrs. Drover has come to London to retrieve some things from their home to take with her back to the city. She talks about how the city is desolate and that there is nobody there to see her go into the house because everyone has left the city.
She had been anxious to see how the house was- the part-time caretaker she shared with some neighbors was away this week on his holiday, known to be not yet back. At the best of times he did not look in often, and she was never sure that she trusted him. There were some cracks in the structure, left by the last bombing, on which she was anxious to keep an eye. Not that one could do anything-
The whole story is set so that Mrs. Drover is completely alone in London. When she gets the mysterious letter, we see the fear creep in, and that the isolation is in itself a danger to her.