Buchanan's De luxe blended Scotch whisky
Couple of options for you to try -
Contact Martin at McTear's - martingreen (at) whiskybids.com
Also, try contacting Buchanan's brand owner which is Diageo. Their archive manager may be able to give you an idea of its worth - but if not, she can certainly give you some info / history on what you have. Email: Christine.J.McCafferty (at) diageo.com
Be sure to have clear photos to send. And let us know what you find out!