This bottle is marked Williams Liqueur, Marmot Kellerei, Zurich, Suisse. The cap has the number 43. The bottom is marked WTK 0,71. I do not think the bottle has been opened, but it does not have one of those paper tapes over the top. It was probably acquired by my parents while on a Caribbean cruise in the 1970s or 1980s. I have been unable to find anything like it in a search on the internet. Any ideas on its age, value, or even its drinkability would be appreciated.