Poul Anderson, The Shield Of Time (New York, 1991).
In spring 1987, it has rained and scents of blossoms and green plants enter the open windows of Manson Everard's New York apartment. Everard mixes Scotch and soda at the bar for himself and one guest. (Scotch saved the universe in an earlier story!)
In 1988, Everard listens to Bach's St Mark Passion, recorded in Leipzig Cathedral on Good Friday 1731. Wanda, hearing it in the background when she rings Everard's unlisted number, realizes that he is not a "'...simple Garrison Keillor farmboy..." (p. 101). (I had to google "Garrison Keillor.")
In 1990, the little bar and the crossed spears and helmet are still in the apartment but the floor is bare. The rug had got scruffy and visitors had reproached him for it. His study's dummy computer conceals Patrol technology.
Later in 1990, there is lightning at night, matching Everard's mood. More Scotch and soda from the bar. Our last sight of Everard in the apartment is of him looking through an open window at wind and lightning.
We want to see more but Everard could not have stayed in that apartment indefinitely if the series had continued. In 2000, he would be officially seventy six and would have come to the end of the 1850-2000 Patrol milieu. So where-when next?