MattThr wrote:The friend in question found it in his attic when he moved in to a new house and is completely convinced it's going to be amazing.
I don't know what part of the "UK" you're in [I imagine that John o'Groats is a little cooler than Land's End], but here in the United States, an "attic" gets to be about 125°F to 150°F in the summertime.
A single afternoon - not to mention 40+ years - of those kinds of temperatures might not have left much in the bottle.
You might look to see whether there's been any seepage - whether at some point the heat had forced the wine to expand out around the cork and leak out onto the bottle [with seepage, you might see a sticky residue oozing out of the tinfoil, or stains as the wine dripped down the label].
Also, you'd want to look at "ullage" - the extent to which the wine has simply evaporated out of the bottle [it could be that the bottle is already half-empty from evaporation over the years].
Chances are that it will be vinegar [or worse], but on the other hand, 1959 was a pretty famous year, so who knows?
If he opens it at a big party [birthday or anniversay or whatever], then tell him to assume that it will be like a foul, spoilt vinegar, and to have backup bottles ready to open when that proves to be the case.