Cutty Sark - Age & Value?

Hello!

I have a One American Gallon bottle of Cutty Sark Whiskey that I ìnherited from my late father.

As far as I can recollect it would be 40 + years old. The cork had dropped in to the bottle (with age) and was recorked this year after we had a quick `tester' (still tastes pretty good) and is 95% full.

How would I find out the age and does it have any value beyond being a bottle of whiskey.

On the bottom it is imprinted with
BERRY BROS & RUDD LONDON ENGLAND around the edge
2 (S) 10:
T Z in the middle

Would appreciate your help!

Thanks - Andy