I have in my possession a bottle of Chivas Royal Salute. My dad claims it had been sitting in my grandmas house for 20 years and was bought in Brazil before they moved to the U.S.. So on top of the whisky already being aged 21 years, it was bought 20-30 years ago, making it 40+ years old.
How would I be able to confirm its age?
Is the quality of the whisky better?
I doubt it was stored correctly, so how should it be stored from now on?