Once a whisky is bottled it does not continue to age. For the 50-year-old whisky to have survived (in its bottle) WWII bombings and earthquakes in the 1940s it must have been distilled in the 1890s, at the very latest. However, the distillery opened in 1921.
The Ferrari in the courtyard of the mansion is a 288 GTO which was not released until 1984, five years after the story is set.