Rare Bottle Of Old Parr??

My sister-in-law is in possesion of a bottle of Grand Old Parr Scotch Whisky that does not have a aged year on it. Instead, in place of that the words listed in that spot say: Real Antique and Rare Old. The very bottom of the label reads as follows: 75cl Gay Lussac 43 followed by a degree symbol. This seems to be a rare bottle and I wondered if you had any information or pricing on it. Thank you for your help