Old Champagne

[17562306]

First of all I am ignorant to all things Wine. That having been said, when I was in the military,in France (before they kicked us out) in 1961, I purchased a bottle of Champagne, and it is still stored on it's side in the cellar , in the dark.
My question is...what are the chances the contents are still good, and while I realize I probably should have picked a wine to bring home, I have the Champagne.
The label reads
Charles Heidsieck
Reims
Product of France
Vintage 1955.
So if you have an opinion (other than dumb dumb dumb) please educate me.
Thanks
Jerry