Re: Glen Grant 1950. Bottled when?
No exact answer can be provided to your if the year of bottling is not mentioned on the label. G&M can bottle the same vintage for several years (e.g., Strahthisla 1964). Each time that a batch of a vintage is sold out, they bottle another batch until they decide to stop bottling that vintage.
Based on the size (cl) of your bottle and label, some guesses can be made.