50 year old?
To be clear - the scotch doesn't age in the bottle - the age that is printed on the bottle is the age of the scotch. Therefore if it is a 18 year old Knockando bottled in 1940, it is still a 18 year old scotch in 2008.
That doesn't mean it may not have collectible value, though.
I was always curious about the Knockando - right next door to MacCallan I believe.